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2004 RSX Type-S - Progression and rationale of mods
Last update: April 28, 2022 -- Also check my ECU tuning blog

When I first got my brandnew Acura RSX Type-S in November 2003, I didn't know where to start. Fortunately I found the ClubRSX.com website and subsequently spent many hours reading posts and learning stuff, then asking questions. This became pretty much an obsession for the next few years. This is a progression of my mods, and their respective pros and cons:

1) 17-inch wheels (Dec 2003) - I ordered a set of 17s with 225/45 tires the day I bought the car. I just didn't feel the stock 16-inch wheels looked right. The set of wheels from tirerack set me back about a thousand dollars, but I never regretted it one bit. However, I did do my research about weight. You want the lightest possible wheel/tire combination or else you'll lose performance.

2) Comptech Icebox (Jan 2004) - I got this because Comptech was just ten miles from where I lived at the time, because the Icebox looked just like the stock airbox but with better breathing, and because it was CARB-approved. Comptech installed it for me. It gave the car a very slightly throatier sound. I dynoed the car before and after it and found I gained maybe four or five horsepower. Not a great return on investment.

3) Comptech street header (Jan 2004) - I got this because Comptech gave me a good deal and they installed it while they installed the Icebox. It looks nicer, but truth be told, I don't think it makes much of a difference. No "street" header does. I like knowing I have a Comptech header, but that's about it. I don't think it warrants the cost.

3) Mugen Sport Suspension (Jan 2004) - The RSX even in stock form sits too high, and my 17-inch wheels made it worse. I did some research and found I didn't need adjustable coilovers and I didn't want just springs which would then wear the non-matched shocks too quickly. So I got the Mugen SS (around $1,000) which replaced all four struts with parts that look almost the same, but lowered the car 1.5 inches and has tighter spring rate and different shock dynamics. I put it in myself and absolutely loved it. This is the way the RSX was supposed to be. Sadly, one of the Mugen shocks blew out a few years (but only a few thousand miles) later and so I took it out again.

4) Hondata #4 reflash (Feb 2004) - I first agonized over whether or not I wanted to have something done to my ECU. Curiousity finally won and I am glad. The Hondata reflash transformed the car. The lowered VTEC point meant a lot more punch in the midrange (I got around 20 extra horses and pounds of torque at 5800 rpms). The car felt smoother throughout all rpms, and on top you no longer ran into the factory rev limiter. Being able to occasionally take the car into the mid 8000s is so much fun.

5) Fujitsubo PowerGetter catback (Feb 2004) - I agonized over the exhaust. All exhausts claim to make 8-10 extra horses, but I had my doubts as the stock Type-S exhaust already seems quite good. I didn't want one that was too loud. So I read through everything and the ratings on this site suggested the Fujitsubo was a good compromise between power and sound. And I liked getting something from a Japanese company that specializes on exhausts. The PG went on in 20 minutes or so. It is definitely louder than stock and you can always hear it, but I do like it and would get it again. I do not know what it did to power.

6) Hondata K-Pro (Apr 2004) - As soon as the programmable K-Pro became available I became obsessed with it. I went to Torrance and took the Hondata K-Pro seminar. I got one of the first K-Pros and absolutely love it. It is the ultimate tuning tool, no matter what mods you have on your car. This is the most important mod you can have, and one that keeps growing with your car. The upgrade price of $500 for reflash customers is very reasonable, and there is an enthusiastic K-Pro user community that is always willing to help K-Pro newbies.

7) Hondata Intake Manifold Gasket (Apr 2004) - It's just $70 and seems like a good idea: keep the hot cylinder head from heating up the manifold. It is a total pain to install, but I am glad I have it. I have no dyno evidence on whether it adds power, but the intake definitely heats up much more slowly, and cools down more quickly with the motor running.

8) AEM cold air intake (Jun 2004) - The Comptech Icebox had never been a happy match with the Hondata reflash, but it worked great with the K-Pro. However, when I had my car tuned and dynoed at Church Automotive Testing by Hondata, we found that the car made much more torque and 8 peak horses more with a CAI, so I switched. Installing the AEM CAI was nowhere near as bad as I had feared, even relocating the windshield sprayer bottle from the left front to the right front as no big deal. Getting the CAI was one of the best things I did. It pulls harder, has none of the throttle lag some people say it has, and sounds awesome when VTEC kicks in. A must-have.

9) ITR manifold (Jul 2004) - I got the Japanese market manifold because it has slightly thicker runners and looking at dynos suggested it would add maybe 5 horses at the top and extend the power peak by a few hundred rpms without compromising power in the lower rpm range. It was a total bust for me. Though I used the K-Pro to optimize fuel for it, I lost a lot of power in the midrange and gained just a little bit on top. The ITR manifold only works if you also have the ITR cams. I took the manifold out and sold it.

10) B&M short shifter (Aug 2004) - The stock Type-S shifter is a total pain and really a disgrace for a car as good as ours. After reading all the stories of breaking Revo kits I decided to wait for the costly B&M kit. It went in just fine and I definitely liked it. It didn't transform the balky RSX shifting mechanism into something truly smooth, but it was a lot better. initially I experienced none of the problems some others have, but around August 2005 2nd and 4th barely went in anymore and often popped out. I examined it and found a serious design flaw that bent the entire thing and made it useless. Replaced it with a Competch short shifter later.

11) Cosmetic stuff - Wherever I went, I saw cars with redded out taillights and blacked-out headlights. After a while that started looking really good to me. So I ordered red-out vinyls from decalgirl.com for a few bucks and put those on (with just one little wrinkle). Then I had a guy with the ClubRSC moniker Jay Type-S black-out my headlights. Jay's a total expert and I thought it was a better solution than buying cheap eBay replacements or expensive JDM parts that are designed for driving on the other side of the street.

All of the above mods probably cost me about $4,500. That gave me a car that is very noticeably quicker and looks, sounds, and handles much better. I also had tons of fun doing it all, and driving the car is a blast.

That was the end of my normally aspirated days. In November of 2004 my RSX became the first customer car to get a Comptech Supercharger, so...

12) Comptech Supercharger (Nov 2004) - I was just about ready to buy a Jackson supercharger when Comptech indicated they were almost done with theirs. Since I live close to Comptech's facilities in El Dorado Hills, CA, I decided to wait. Comptech installed their Stage 1 supercharger which uses the latest version of the Eaton G62 positive displacement compressor. Even with the stock injectors, power went up to 232 whp and the car felt terrific. For a dyno showing the street Comptech supercharger kit versus stock with just the Icebox intake, click here.

13) Comptech titanium front strut brace (Nov 2004) - This good looking brace replaces the weaker stock brace. It increases the structural integrity of the front suspension. Did I mention it looks terrific?

14) Comptech rear sway bar and tie bar (Nov 2004) - The Comptech bar is thicker than the stock sway bar and reduces leaning. The tie bar is a beautifully manufactured piece of billet aluminum and strengthens the part of the chassis the sway bar bolts on. It also looks great from behind. It really does.

15) Boomerang Armrest (Dec 2004) - Got that for Christmas. Very well made and engineered and covered in black leather that matches the RSX seats perfectly. It neatly seats in one of the console cubbies; you don't even have to screw it down. However, it's a bit high. With my arm resting on it I have to reach down for the shifter. I eventually removed it after a near misshift which I blamed on my arm resting too high due to the console.

16) Auto Meter Sport Comp boost gauge (Jan 2005) - I sprang for the more expensive full-sweep model that has its own MAP sensor. Toughest parts: finding a 12V source that does not go off during starting, and splicing into the dash lighting so that it dims. Works great, and the Auto Meter column mount pod is ingenious.

17) Comptech supercharger Stage 2 (April 2005) - I had been road testing Comptech's supercharger for over 4,000 miles and all went well, so when Comptech was ready we installed a smaller pulley and larger injectors. Power went from 232whp to 258whp. For a dyno sheet showing the difference between the street kit and Stage 2, click here.

18) ACT Performance clutch, heavy-duty pressure plate, Comptech lightweight steel flywheel and Quaife LSD (May 2005) - With almost 100 whp more than stock, I felt an upgrade to the clutch was in order. I wanted something that could handle my torque, but still be okay for the street. I got the ACT performance disc, the ACT Heavy Duty pressure plate, the Comptech lightweight steel flywheel (9.5 pounds instead of stock 16 pounds), and a Quaife LSD. I expected a substantial difference, but the clutch and engine feel almost the same, which is good. The LSD makes the car feel like on rails, and both wheels now spin in unison on launch.

19) Boost increase (August 2005) - I had Comptech replace the Stage II 3.6-inch compressor pulley with a 3.3-inch pulley. This increased boost from about 6 psi to around 8-8.5 psi. Extensive retuning was needed and the car eventually reached 290whp on Driving Ambition's dyno. Given that this is at the wheels and there's about an 18% loss between crank and wheel, that would translate to 354hp at the crank.

20) Hondata K-Pro upgrade to v4 (February 2022) - Back in 2004, I got one of the very first K-Pros. Hondata added many features in the meantime, and so I decided to upgrade my K-Pro to version 4. Sent in the K-Pro to Hondata. Got it back with the daughterboard ill-fitting and loose screws, and found that you have to register your K-Pro with Hondata, stating that you won't use your car on US roads unless you're registered with a racing organization and only use it on tracks.

21) Kenwood GPS navigation system (March 2023) - I was never very impressed with the Type S' OEM old-style sound system. Bought a Kenwood DNR476S head unit a year ago and just now put it in. A bit of a pain, and what a huge bunch of wires and connectors! But it works great, and I love having Apple CarPlay in the RSX!

21) Acuity 4-way adjustable performance shifter (March 2022) - The Acuity is costly, but oh so nice. This was my third shifter replacement (stock to B&M, B&M to Comptech, and now Comptech to Acuity). Love the Acuity! It is infinitely adjustable and feels MUCH more precise.

March 15, 2023: Well, I still have my 2004 supercharged RSX Type S. I am the original owner, the car has still only 28,000 miles on it, and it spent every day of its life in a garage. Next I'll have the local DentStation fix a couple little bumps, and replace the (too-harsh) lowered stock springs with a set of front and rear strut & spring assemblies from TRQ. I had looked at various coil-overs, but decided on the TRQs that look almost exactly like the Mugen Sport Suspension that I had years ago, with a 1.5-inch drop..

Questions? Email me at conradb212@gmail.com