Tested: Full Race Catless Downpipe for 2012+ Civic Si

A frequent question that gets asked is “What downpipe makes power on my 9th gen?” I have gotten in the habit of simply directing people to Full Race Motorsport’s website as we use their catless downpipe & exhaust on our supercharged vehicle, and I know the setup makes power.

Now here’s empirical evidence that it does.

Philippe was down at the shop and had us install the Full Race catless downpipe before I tuned his 2012 Civic Si. The vehicle came in with the following modifications on it already:

  • Invidia Q300 Exhaust
  • HPS Intake Hose
  • K&N Drop in Filter

Now from previous baselines of completely stock 2012 Si’s, I know they do about 160-164whp on our shop Dynapack. Before we installed the downpipe we baselined the car as it arrived. Sure enough, it did about 162whp with the power curve I’m used to seeing on a stock 2012 Si. This leads me to make the following conclusions:

  • The HPS intake hose and K&N drop in filter do absolutely nothing. Pretty pointless modifications and honestly a rip off (spend your money elsewhere).
  • The Invidia Q300 is a nice sounding exhaust, as always, but does not make any power, at least not without a tune. Maybe this will change with a tune?

We installed the catless downpipe, and put the car back on the Dynapack and randp_vs_nodp a couple more baseline pulls on the stock tune. The results are as follows — solid line is with the downpipe installed, dashed is before the downpipe.

We netted as much as +10whp and +10wtq from simply installing the downpipe. That’s a sizable gain for a simple modification.

tuned_dpNow let’s throw a good tune on the car… and the results are as follows. Solid line is fully tuned, dashed line is our baseline with the downpipe installed. The tune netted as much as +12wtq in spots and as much as +18whp on the top end.

dp_tuned_vs_nodpWhat’s this look like over the original baseline before the downpipe was installed? Here you go. Netting almost +30whp in spots with a downpipe and tune on the top end. Sizable gains, the part worked well and the tune brought it all together.

How does the exhaust factor into the power curve? Until I do a fair comparison of an exhaust swap on the car I can’t say with absolute certainty. However, we do know what other parts do make power already — A CAI nets 4-5whp, which would put this car around ~190whp, which is about 3-4hp shy of what the average 2012 Si maxes out with using bolt ons on this Dynapack dyno. So to make an educated deduction — an exhaust may net 3-4hp and maybe some mid range torque due to the ability to adjust the variable valve timing on the motor. It also seems that a 3″ exhaust would be the way to net any power at all, and anything smaller may not net any gains. With the integrated exhaust manifold design on the 9th gen cylinder head, the gains we’re used to seeing with a 3″ exhaust on previous K series engines don’t really hold true on the K24Z7.

Safe to say — if you want PROVEN performance, a good catless downpipe (Full Race works well as I’ve shown) and a good tune will get you 95% of what you’re going to get N/A with bolt ons. A cold air intake will net some power as well — and the exhaust is a wash at this point it seems.

Honda Tuning: What the hell did I just look at?

Introduction (bear with me!)

In an era where the Internet is “king” when it comes to information sharing, gathering and overall knowledge — it’s amazing how much misinformation (whether just misleading or straight up lies) there is to wade through in the “tuning business” — especially where it comes to the Honda market. Sometimes it’s even hard to discern what is fact and what is fiction — there are so many “big names” out there with fantastic accomplishments that arguably should be contributing to the fact pool. Unfortunately in a market that is cut-throat it seems many are content to just “do what we do” and keep pouring bucket fulls of garbage into the fiction pool. Whether it’s simply due to ignorance, catering to a target audience or just to make a quick buck — I do not know. I’m going to take some time and share some facts about “what the hell did I just look at?”.

Now before someone gets their feelings all hurt and goes on some tuner battle rampage — I’ll say this: I do not care about your feelings and you can’t hurt mine. You have no idea who I am and why I’m in this business (it’s not the quick buck — if I wanted to get rich I wouldn’t be tuning cars).  I am not naming names. Not only is that unethical, but it just plays into the same garbage bag of fiction this industry is flooded with.

Everyone who’s spent time talking with either myself personally or been to the local shop knows one simple truth about me — I am brutally honest and my whole goal and business ethic is to provide the best product with the best support in the industry. Your project is my project — if it’s something I personally wouldn’t be happy with driving day to day (for the street cars we work on) or taking down the track, then it’s not good enough and it needs to be looked at until both myself and my customer is happy before I sign off on it as “complete”. Another fact few may know — back when I first entered the Honda market I used to do the tunes for free. Why? Countless complaints from members on various online forums about their vehicles after they were “tuned”. In an effort to help the respective communities I offered a helping hand to share my experience and get people on the road and enjoying their rides. Obviously a business model of “free” never paid the bills nor compensated me for the time invested… So here we are today — and a midst an industry where many didn’t greet all our methods with open arms (to put it lightly) we’re still here and not going anywhere.

So what is the point I am getting to? I have always had an open door policy — not only free touch ups on any tunes we’ve done over the years (on vehicles where mods do not change) but also free datalog reviews for anyone concerned with how their vehicle is running, whether it be on a basemap or a 3rd party tune. I want to share some facts about what you want to look for to make sure you got not only the tune you deserve — but the tune you paid for (remember — you’re paying for the knowledge and experience of the tuner of your choice… you’ll be surprised what you get, even from the “big names”). There is so much that can be discussed — so I will just limit this post to Honda K series, as of this writing it is a widely popular platform.

 Wide Open Throttle

Rather than try to show you what you SHOULD see, which can vary a bit with the application the vehicle/build is targeting (yes, you tune a road race car different than a drag car which is also different than a street car…), I will show examples of what you should NOT see in the frame of a pump gas vehicle. Not only is the K series a VTEC motor, but it also has variable valve timing — VTC. Something many tuners seem to forget, or simply do not understand? I’m not going to touch upon ignition timing as that discussion is a very lengthy topic on it’s own.

The vehicles in the following example are powered by a K24Z7, but the same information applies to the K20A/Z and K24A variants as well.

During wide open throttle the vehicle should be running in “open loop”. What this essentially means is it’s running a fixed set of values and compensations (IAT/ECT and the like) to hit optimal targets — the ECU cannot and will not change these values based on certain sensor feedback (IE, changing the fueling based on the O2 sensor reading).

cam_example1The following graphic demonstrates a very poorly tuned WOT (wide open throttle) supercharged vehicle. The fueling (AF.Corr value) is extremely lean through a vast majority of the pull. The cam angles (VTC) look like they were touched — but not even remotely close to optimal on the setup. VTEC was also not properly set — ~4100 rpm on a CT-e supercharged internally stock K series is just silly. To top that off — the car was actually tuned on the dyno (I typically am a bit lenient in what I see on street tuned/eTuned vehicles I review unless the mapping was blatantly a mess). How this can even be remotely possible given the tools for the tune were in a controlled environment…? Simple: lack of experience of the hands working the tools… the tools themselves are not always to blame.

cam_example2Even worse… here’s the SAME problems on ANOTHER car with a CT-e kit. Same exact issues — but even worse, the cam angles are basically what a completely stock (unmodified) vehicle runs. VTEC is also at the factory point…. which is beyond silly on a car with a blower on it. Also tuned on the dyno. I’m just appalled.

cam_example3But wait — this isn’t just plaguing CT-e cars, the Kraftwerks cars are getting hit just as hard. Even worse this time — 16 AFR while in boost? That is beyond ridiculous — I’m surprised this motor didn’t melt a piston or two. VTEC wasn’t even remotely accurate and the VTC settings were a far cry from optimal. Also a car that came off the dyno, done by a shop that has some wicked fast cars (actually all 3 examples were).

I could go on — I have examples of turbo K series that are just as interesting. But it just gets more and more depressing, and that is not the goal of this thread. It seems that way too many tuners are simply not well versed in what is required to properly map a cam phasing/VTEC motor — and that is just unfortunate, as customers are shelling out money for what they believe is a good map.

cammapEven worse — we have your average copy and paste K series tuner. What does this mean? On your typical K series map, you have 5 or 6 cam angle “break points” for fueling and ignition for low cam (VTEC OFF) and 5 or 6 cam angle break points for high cam (VTEC ON). Proper fuel mapping of a speed density (“VE” — volumetric efficiency) calibration requires mapping each of these individually because as the cam moves, the fueling demands of the motor will change drastically based on the requested position of camfial1the cam. So what’s the copy and paste map? That’s when a fixed fuel map has been copy and pasted across every break point (example to the left is one of the above CT-e S/C tunes — I only show 0 and 30 as the car was not even mapped past that). You can see they are identical in the example. A properly tuned map camgoodwill look something like this example to the right. Notice how the are drastically different? Because the engines demands when the cam is at that point is that much different! Why is this important? I address that in THIS article. When I see a copy and paste map I ask myself: “What exactly was tuned?”. It’s a 20 minute map if I’ve ever seen one: rip it and ship it. There are a couple of exceptions to this — one example being if you run a very aggressive cam that can’t make it to say — 40 or 50 vtc without making piston contact, then you cannot map those break points (and should not try) and you don’t have to change them or you can just copy & paste your last tuneable break point to them (for example if the cam was safe to 40, you can paste the 40 break point to the 50 break point or just leave whatever is there as the ECU will never reference it).

I have heard such excuses as “well it’s a turbo car which will just blow boost out with more cam timing”, “I spent ALL DAY on the dyno, it’s fully optimized!” and “well the O2 sensor is just wrong or the fuel trims are screwing it up” (which can be a silly excuse when the car in the example also has an AEM wideband in addition to the stock one and they match exactly…).

Yeah…. no. I tune the exact same cars, with the exact same setups, and I have tuned a LOT more of them than any local shop has tuned. I can recognize a faulty O2 sensor 99% of the time just from the datalog (yes sometimes an occasional one will slip by — they can be sneaky). If you spent “ALL DAY” on the dyno and produced the ticking time bombs from the example above or turned on closed loop at WOT (by default all these cars will go “open loop” the moment the car is making boost) — rethink your career choice. It may be hard to sift through the fairy tales sometimes — but open your datalog and look for yourself.

Wait again — I have one more excuse, and this is my favorite: “it made power on the dyno, you saw it!”. Sure, it did. Even the worst tunes will make peak HP numbers that look good — especially when you throw forced induction at the motor (what’s a motor to do when you’re cramming air in there??). We can really be tunnel visioned by the peak numbers from a dyno chart — so much so that we miss the bigger picture: the full curve. The examples listed above are what I’ve classified as your classic “start the dyno pull at 4500 rpm and stop at rev limit”. Great for numbers, but not very useful in the grand scheme of properly mapping a K series vehicle. What about the whole curve? What about everything down low and mid? These are some things we should be thinking about when handing over our vehicles to be tuned. In every example above the car made better power across the board — not just better, but safer as well.

You might be going — hey Vit how do you know? Well… going back to… I work on the same cars and have been through many more of them than any shop you can name. I do not want to post examples of what properly mapped cam angles, etc, are, they will vary a bit from car to car, setup to setup — on top of which there are some places that love to pass off other people’s work as their own just because they added 1 degree of timing or changed the cam angle 5 degrees (I can always tell when a shop ripped my map off a customer’s car and use it as one of their “own” — my techniques are quite unique and I can spot my maps very quickly). The above are just some examples are of things you SHOULD NOT see on a properly tuned vehicle. Feel free to message me if you have questions and I’m more than happy to have a discussion and share some knowledge.

 Part Throttle

Among the ignition and cam angle mapping you also want to optimize closed loop fueling on the vehicle. I will not touch on the cam angle and ignition aspects as that would simply be way too much to write about, and there is a fair bit of leeway on how you can map VTC (cam angles). Ignition also isn’t nearly as sensitive at part throttle loads due to much lower cylinder pressures (although if timing is way too low it can and will affect drivability).

So assuming a clean ignition map, the most important aspect is to get fueling at light loads as optimal as possible to keep the closed loop feedback to a minimum. Why is this? Because the “tighter” the “trims” (short term and long term) that adjust the fueling to keep the car near stoichiometric during light acceleration and cruise, the smoother and better the car will drive (and make a bit better power). What closed loop does is essentially add or subtract a “trim” to get the fuel target back to stoich — ~14.7 AFR — under light loads. This also ensures good fuel economy. You can view these trims as “STRIM” and “LTRIM” or a similar name in most engine management systems. On most Hondata systems “LTRIM” is typically 0 as it has been disabled, and the ECU only uses the “short term” (STRIM) trim.

So what happens if these “trims” are way too great in one way or another (to far negative or too far positive)? You now start experience weird issues — bogging out, hesitation, misfires, car stalling out and the list goes on. Sometimes the car is essentially undrivable — even though it “made power”. Just because the car was “tuned” doesn’t mean the whole map was given full attention — I have seen this so many times that it’s basically the “norm” in the industry. Too many of the uninitiated in what a “good” driving car is swear by tunes which are far from good or smooth when in actuality they have no idea they are literally behind the wheel of a car that drives like complete crap. Yes, I said it, crap. This isn’t meant to hurt feelings, it’s a matter-of-fact statement. Sometimes we just don’t know what we’re missing.

So where’s a happy medium? Rule of thumb, acceptable is +/-10%. Where I like to see it? +/-5% if possible.

strim_exampleI will share two examples of what you don’t want to see. First one is actually an eTune done using speed density fueling I had the pleasure of reviewing for a fellow car enthusiast. One way to view the trims is to add them to a graph view, which is what I’ve done in this example — we’re at -25% and the car is STILL rich (13.8 afr) coming to idle. The complaints on this vehicle were of hesitation, bogging and the idle wanting to stall out. We can see why…

In the next example we have a newer Acura that is only tuneable via AFM (no speed density on this platform). You before_histocan put such a vehicle log into a histogram to review the fuel trims. It was painfully clear that the person mapping this vehicle had no idea what an AFM was or how it was properly calibrated. The ECU was sitting well into the -30% area (worse actually after the LTRIM was added in) with a “mean” (average) of about -22%. This is just horrible. In practice you should see something like now_histowhat you have in the following graph to the right. We are mostly +/-10% with a mean of +/-5%. Because of how AFM cars run and transition into open loop,  the ~3.5v to 4v area on this vehicle being around ~-12% is actually acceptable — granted not as ideal as I’d like it to be, but sometimes you have to make a small compromise — and in this case its only really 2% away from “acceptable”, and has  no impact on drivability compared to the prior mapping that was on this vehicle.

Dyno vs eTune

This is by far the silliest argument I have ever had to take part in. There are good dyno tuners. There are good eTuners. There are horrible dyno tuners. There are horrible eTuners. Easily summarized: there are great tuners and there are horrible tuners. Just because you chose one method or another does not guarantee you a “good” tune or a “bad” tune.

There are shops that vocally hate eTunes — good for them. They have a business model to protect — and most have no clue how a proper eTuning is even done! Unfortunately a vast majority of them will lie and coerce some customers into a dyno tune. To me that is just a horrible display of integrity.  I have never had to coerce a customer into an eTune or a dyno tune by hyping up one method or the other — and what some shops don’t realize (or forget) is I have been doing this over a decade, on dozens of dynos of all kinds and via street/eTune. I like both methods and believe there is a good harmony to be had with the two — ultimately the experience of the hands behind the computer doing the mapping is going to determine the final product, not the method.

Yet there is a rampant collective if no-name mom & pop shops that have effectively no real tuning experience — but since they own a dyno they are automatically professional tuners and because their dyno spits out numbers for such and such setup that automatically makes it a “good” tune and a “good tuner”. Newsflash: the dyno sheet does not dictate tuning ability nor does it determine how the vehicle performs (how “fast” it is). They are a tool, nothing more. That’s it. Ultimately the numbers you get from any dyno are absolutely meaningless without context. Guess what? Your typical roller dyno is cheap — $15k – $25k installed for a standard inertia type dyno. Any automotive shop can afford to lease one over the course of 5 years (standard lease). Too bad you can’t just buy personal tuning experience with a credit card…

The back and forth on this topic has however created some very amusing aspects. Namely one big one and I like to call it “jumping on the eTuning bandwagon”. Mail order tunes have always been around — it’s big in the Ford/Dodge flash device market and even on platforms like Mazda/BMW/Chevy. I have had the great pleasure of promoting the eTuning market to where it is today in the Honda/Acura word, and my popularity has been a great indicator of this. I have a passion for what I do and I’m not going anywhere — and I appreciate all the support my business has received over the years.

Due to my success, I’m seeing more and more so called “haters” now jumping on the band wagon. Everyone wants to be an eTuner now that we’ve proven there is not only a demand, but a NEED for it (not everyone has a good tuner nearby…). The level of hypocrisy (irony maybe too?) is just astounding. The unfortunate aspect here is — producing a good eTune is actually harder than a dyno tune. There is more work and more thought involved in the how and why of what you are doing. Bluntly put — we have “tuners” that are releasing under par work from the cars they put on the dyno now trying to eTune the said cars. How can one expect a good eTune from shops that are releasing tunes like in the previous examples? Bluntly — you can’t.

Anyone claiming an eTune is “easy” has never done an eTune properly — sending out a generic basemap and just fixing some fueling is by far NOT a full and proper map. Others will send a map from a previous car they’ve street/eTuned or dyno tuned and again — just fix the fueling for you. Hell some even advertise as much. There’s nothing custom about it and very little actual tuning is involved. It’s down right shameful is what it is and the results are far from amazing.

It’s definitely easy though — easy money too, right? Easy to catch a new comer into the “tuning scene” and take advantage to make a few bucks. And then easy to write it off to “oh well you only paid for an etune,  you need to go on a dyno”. Yeah right. This isn’t what my reputation is founded on and we’ll never go that route — every map is tuned from the ground up, a truly custom experience. Every car is different (yes even with the same mods) — and should get the attention it deserves (and that you’re paying for).

But hey, with a market where your entry only requires you to own a laptop and download some free software — anyone can be a eTuner! Or at least play like one — and unfortunately I do have to say that the vast majority of sites popping up offering eTuning services are nothing but crap and are run by complete hacks. It actually pains me to say that as I support eTuning and it can be done quite well in the right hands (I’m very successful with it — spawning some of the fastest K series vehicles in the 8th and 9th gen markets!).

On the flip side — the vast majority of dyno owners have no idea what they’re doing with an ECU beyond the graph that is printed out on their dyno computer. I guess that makes for a happy medium?

Really though? It just sucks for the consumer.

Final Thoughts

Some people may now go — wow Vit you’re a complete asshole. I’m sorry you feel that way — maybe one day you’ll get a chance to meet me and form a real opinion. I certainly am not motivated to be an asshole — what drives me to succeed and pushes me to try and be the best at what I do is my passion for my work and my desire to never see a fellow car enthusiast with a vehicle that’s been butchered. I’d rather be an asshole and have someone with a car they enjoy with the support they deserve than to be your best friend and leave you with a car you don’t want to drive. But hey if I make a friend while taking care of a customer — even better. I’ve build some great relationships between many customers and vendors — and I hope to keep that ball rolling.

Hopefully I gave us all something to think about — and some insight into what to look out for so we’re not caught asking ourselves: “What the hell did I just look at?” The haters can continue to hate all they like — I’ve found the more they hate, the more it indicates that I’m doing something right. I don’t know who they all are — but apparently they know me. Speaks volumes I think? While they spew senseless ramblings on whatever Facebook section is popular that day about “what they heard” and “just saying” with the vocabulary of a 3rd grader I will continue taking care of my customers, improving rides worldwide, going faster and bringing new products to market.

In closing — they may try to duplicate, but they can never replicate. If you want the best your money can buy — you know where to reach me!

2012+ Honda Civic Si RBC Intake Manifold Test


There has been an ongoing debate about the pro’s and con’s of swapping the 8th gen Civic Si intake manifold onto the 9th gen Civic Si without any real concrete testing. Just butt dyno reviews, bromancing and numbers being thrown around with no context. So basically your average day on an enthusiast discussion board.

We’ll be having none of that here — I requested a 2012+ Civic Si that had a Full Race exhaust and Full Race 3″ catless downpipe, running the stock intake as our “base” to start from. We also got the the PRL SRI for the stock IM & RBC so that testing would stay consistent — and we tested the PRL SRI before installing the RBC IM.

So in short the testing involves:

  • PRL SRI on stock intake manifold.
  • RBC intake manifold w/ PRL SRI (to see difference over stock manifold).
  • ZDX throttle body.

Now the ground rules are simple:

  • The vehicle must be fully retuned after each major modification change on the vehicle.
  • No “snorkel modding” the intake out of the engine bay to artificially reduce intake air temps (reducing air temps will indeed increase HP — the goal of this test isn’t to show you this). The goal is consistent and realistic testing (particularly to demonstrate differences from mod to mod).
  • Two to three pulls are done on the “final” tune to ensure the engine has “settled” and the pulls are consistent between attempts — maintaining this requirement ensures comparisons between the various mods we are testing are consistent.

Long and productive Saturday: eight hours without the car leaving the shop dyno and over 70 dyno pulls later, we had concluded testing.

Now on to the results.


Stock tune vs VitTuned

stockintakeThis is how the car came in today. Equipped only with the Full Race 3″ Exhaust and Full Race 3″ catless downpipe.


I baselined the car on the stock tune and we got just shy of 180whp (the dyno baselines 162-165whp for a bone stock 2012 Si). Not bad at all for two simple exhaust bolt ons. The stock intake had been retained and this example demonstrated why I recommend keeping the stock intake if you can’t afford FlashPro/Tuning yet — the car actually runs mostly OK with the factory airbox on the vehicle. Obviously doesn’t make “best power” for the mods, but the car drives and performs well day to day.

I proceeded to fully tune the car — and the power went up nicely with a cleaner power curve throughout the rev range, stopping just shy of 190whp — with gains of 11-14whp through the top end over the factory tune.


Stock intake vs PRL SRI

prlsri_stockimI proceeded to install the PRL Motorsports short ram intake (SRI) on the vehicle. Fitment was perfect and install of the SRI was a breeze — requiring only a couple of basic tools.prl_sri_vs_stock_intake_stockim

Back to the laptop I went and more tuning commenced. I was pleasantly surprised by the solid low end gains from 1700 rpm til 2500 rpm — as much as 12 ft lbs of torque to the wheels will definitely be something you can feel during normal stop and go driving. Slight loss from 2750 rpm to 3000 rpm though — nothing major. And no real gains until after ~ 5700 rpm, with a maximum of 4.5whp was had from 6750 rpm til 7000 rpm. Not a bad gain for a simple mod — I’ve seen much worse performance from some intakes on this platform (worse than stock intake at times).


And now the RBC intake manifold!

prlsri_rbcimOn to what we’ve all been waiting for! I dug back into the engine bay and worked on installing the RBC intake manifold PRL graciously supplied for testing — as well as their adapter for the kit. This install is a bit more involved than the SRI and required a larger variety of tools — and about 2-3 hours of shop time to install.

Once the intake manifold was on, the RBC IM version of PRL’s SRI was bolted up and the coolant system was burped. This step is very important — the coolant system must be properly burped. I’ve had customers send me datalogs with 280 degree Fahrenheit coolant temps after doing work on the car that involved draining the coolant system — which just guarantees a blown head gasket and very costly repair. I recommend using this kit, or something similar, to assist with purging the coolant system of all air: Spill-Free Funnel.

Back to the laptop I went for another session with the Hondata rbc_vs_stockim_prlsri_on_bothFlashPro. And here are the results!

  • Below 2100 rpm there is as much as 12 ft lbs of torque lost when using the RBC intake manifold.
  • From 2100 to 3500 rpm there are minor torque gains (1-6wtq) when using the RBC intake manifold.
  • From 3650 rpm until 5750 rpm there is nothing but bad news when using the RBC intake manifold — as much as 15 ft lbs of torque lost!
  • After 6200 rpm is some good news — we begin to see minor gains, based on “peak” numbers, we only got a 6whp gain using the RBC.
  • At ~7150 rpm there is a 7whp gain.
  • At 7500 rpm there is a 11whp gain.

So what can we gather from this? There is a hefty trade off when using this intake manifold on the 2012+ Civic Si. You are basically sacrificing a lot of mid/low end for a powerband that carries better after 6000 rpm.

So pick your poison: what are you using the car for?

Racing? Then technically speaking this car will be a bit faster when keeping the revs above 6000 rpm.

Daily driven stop and go “fun” car? The torque with the stock IM might benefit you more.

The choice is yours — as with everything in life, we do what we do with our toys for our own pleasure and enjoyment.


Wait, let’s make a joke and put a huge TB (ZDX/J37) on the car and see what happens?

zdxtb_on_rbcimNow I really have no idea how TB swaps got so popular on bolt on motors. The simple fact is this — items like throttle bodies, injectors (yes I’m looking at the guys claiming RDX injectors are necessary with an RBC IM swap), etc, are nothing more than SUPPORTING modifications, and ONLY benefit you when the motor has a flow requirement that is now surpassed by the items on the car. To say the stock 9th gen throttle body is a restriction on a bolt on 9th is simply a JOKE. The following comparison demonstrates as much. For the marginal gains (1hp) that is had up top with the TB, as much if not more is lost in the mid/low end.

But so and so put a TB on and it pulls so hard…. sorry, please schedule an appointment to have the butt dyno re-calibrated.

Hopefully this has been an insightful test for us all.


What’s all this cost?

  • RBC Bored to 70mm for ZDX and CNC Bored for 9th gen injectors – $420
  • PRL RBC Adapter Kit – $135
  • ZDX TB (when purchased as kit option from PRL) – $220
  • PRL SRI – $200
  • Shop labor (if not installing on your own) — 3-4 hours ($240-$320 here)


I’d like to give a big thanks to PRL Motorsports for supplying us with all the goodies for this test.

Thanks Ernesto for supplying the test vehicle — enjoy the mods and the tune!

Deatschwerks DV2 1500cc Injector Review

Deatschwerks announced their DV2 line of injectors — 1200cc and 1500cc variants — not too long ago. I was fortunate to be one of the first to get the word about these injectors from DW and I was excited to get my hands on both sets to do some testing on my shop vehicle.

Foremost, I want to talk about the 1500cc variant — I’ll touch on the 1200cc set briefly later.

The test vehicle is a 2001 Honda S2000 powered by the F20C on an AEM Infinity stand alone. The fuel system is very simple — the OEM Honda fuel return system with completely stock fuel lines, with a Walbro 485 fuel pump in tank, an AEM FPR and AEM fuel rail sitting over the Deatschwerks DV2 1500cc injectors.

My goal? To make over 600whp (on a dyno that baselined 195whp for the car bone stock) with a Comp CT4x-5862 turbocharger.newmotor_20psi_pump_vs_24psi_e85

Mission? Accomplished. On E85 the vehicle put down over 600whp at 24psi and 525whp on 20psi running 92 octane pump gas.


That is fantastic power for a very simple setup — it’s a 2.0L bottom end with a 58mm turbo and only “drop in” fuel system upgrades (no plumbing new lines, etc).  The only fault in the fuel system is the high fuel pressure at idle — I’ll touch on that later — and the injectors have performed amazing nevertheless.

I am able to run a very wide range of power without swapping parts — no injector swaps, etc. The injectors DW supplied me have been more than plenty for my goal, with room to push to 700hp with a higher base pressure and a different pump/fuel line setup (the Walbro 485 doesn’t do so hot at high base pressures).

Unlike the 2200cc injectors we have been stuck with in the past if you wanted to do a 600whp+ flex fuel vehicle, the 1500’s don’t have the drivability nuances we’ve become so accustomed to — no insanely unstable idle due to the pops and misfires, no weird shuffling at light loads or on deceleration. Even on pump gas — where it is virtually impossible to get a set of 2200cc injectors to behave without running the vehicle at a super rich target lambda.

On E85 the 1500’s have a very slight pop at idle . On pump gas — they are a little “poppy”, but not so much that it deters from the idle or attracts unwanted attention to the car stop light to stop light. Much more than acceptable — they actually make the car very enjoyable to drive without having to put up with drivability nuances. In fact, whether it be on pump gas or E85 — squeezing the throttle rewards you with a smooth powerband, strong spool and very predictable power delivery without the odd “oops the motor missed” as you touched the throttle.

And if the biggest fault I can find with the 1500’s is that on deceleration in rare situations running pump gas I’d get some shuffle — I can easily blame it on the high fuel pressure at idle & low load. With the Walbro 485 in tank, the fuel volume is so massive the small factory return line can’t keep up when the engine doesn’t demand a lot of fuel — this increases the fuel pressure to over 70psi on this car, resulting in effectively a 1900cc injector in these situations. Yet — I was still able to fix the shuffling with a tuning trick, without going to the same extremes as a 2200cc injector.

Better yet — a fuel return line upgrade will bring the fuel pressure down to actual base pressure and clean up that behavior. This isn’t something I’m wanting to do on the car as I have not found it to be necessary — the drivability is fantastic and I just don’t want to change a thing at this point.

Short comment about the DV2 1200cc injectors: they are perfect. In every aspect. If you’re not looking for 600-700hp they’re a great choice as well. I made 575whp on E85 on the 1200’s squeezing them to 100% duty cycle.

Whatever you’re looking for — both injectors are fantastic and I would definitely recommend.  As with all the products I’ve tested and support, these injectors are on the VitTuned Store.

K Series Mapping: Why so many revisions for a proper map?

A question I get very frequently here at VitTuned. The short answer is very simple: do you want it done right, or do you want it done fast (and lazy)?

For the long and descriptive answer, let’s take a look at an example of a Hondata FlashPro (same idea with Hondata KPro and KTuner maps) map. The heart of the tune is the ignitcammapion, fuel & cam angle mapping, with the proper VTEC point being the final slice of pie.

The following graphic depicts these basics — but the thing to note is there are actually *10* ignition and *10* fuel maps, at various break points. So now at the very heart of the tune are 10 of each of the “big ones” (ignition/fuel) that need to be properly mapped for the vehicle & its modifications.

Now we can begin to understand why so much work — not only do you have to do all the individual mapping, you then have to combine it for a “final” fully tuned map, adding in any further tweaks necessary to smooth out the motor’s operation as well as doing any necessary part throttle tuning whimapsle the power tuning has been going on.

To the right is a screenshot of how many “revisions” a proper all motor map involves — this was a tune done in person on the shop Dynapack dyno. Every log is either a WOT pull or load based part throttle mapping while the vehicle was on the pack. Took about 34 “revisions” (IE, changes to the tune before more logging & testing was done).

This is how I do every tune, every single one. Whether it’s your basic stock K series vehicle or highly modified turbo built motor beast. Do it right, or don’t bother doing it at all.

I’ve seen some claim they tune like I do — short story is they may try to duplicate, but they can never replicate.

Let’s dig a little bit deeper.

The most important thing to note is the fuel mapping — on a setup that breaths very well there can be as much as a 30-40% difference in fueling between the 0 degree cam break point and the 50 degree cam break point. Even if you set up the cam angle map to have a mostly “fixed” cam angle map — guess what? The cam still moves, it’s a simple mechanism that’s powered by oil pressure — not to mention the phasing between the high cam and low cam (VTEC on and VTEC off) maps. Then what happens if the ECU ever limp modes for any reason? It will default to the 0 degree maps in the ECU during fail safe scenarios.

So let’s take for example a map where every single cam break point is the *exact* same, they are identical or very nearly so. Or fuel maps that were put together with no thought — I have yet to see a single K series motor that will demand the exact same fuel at every break point. In three words — it is impossible. As the cam angle moves, the VE (volumetric efficiency) of the motor changes, and as a result the fueling demand drastically changes which is then depicted in a map with properly tuned fueling.

Now what happens in this scenario? The cam will phase, the motor’s fueling demand will change, and you’ll start to experience some drivability concerns — some hesitation there, some weird lag here. What if the ECU limp modes? You’re left with a potentially undriveable (if not unsafe to drive) vehicle.

I’ve heard several excuses for lazy K series mapping — “AEM doesn’t  do it like this” (or insert “Blah blah stand alone doesn’t do it like this”) or “you’re obviously getting your information from someone who’s never seen anything but Hondata”. That is by far some of the worst excuses I’ve seen for laziness on this specific platform. And to break some hearts — I tune over a dozen different engine management systems. Simple fact is — you tune Hondata like Hondata, AEM like AEM, SCT like SCT, HPTuners like HPTuners, etc. Every EMS has it’s intricacies — you learn them all, or in my opinion, don’t bother touching it if you don’t have the motivation to do it right to begin with.

So I’ll leave you with that — you can have fast & lazy, or done right (but takes a bit more work). Ultimately it’s the customer’s money paying for the work & experience they’d like to receive.