Also if you could source an AP2 trans that will help you a good bit too. The AP2 trans is geared shorter than an AP1 and it will give you a better low end feel. So my list would be Password or J's racing intake, J's racing header, Mugen header, Toda header, HyTech header if you could get one, a 70mm or depending on your exhaust a 76mm test pipe. I have a Berk 76mm Header back with a test pipe built into it and love it but it is not quiet at all. T1R Sparrow Single I have heard made power after talking to Evasive so did the Challenge exhausts but same thing applies if you can get a hold of one, an AP2 trans and diff for durability AP1 diff can be glass box if you launch it a lot and obviously a way to get a tune. There are few engine management systems out now for the S2000. Should put you some where in the 270-280 crank hp depending on the health of your engine. Another thing to do that I highly, highly recommend is to talk to the companies that build S2000's and race them and have actually done real world testing on what works and what doesn't work and what can work for you for what you want to build. They are truly the experts.

 

270-280 crank HP?! from I/H/E? Surely, you jest.

If that were the case, the cost of those parts would be worth the cost.

Bolt ons flatten the curve...but they don't typically add much peak HP.

OP isn't after peak HP anyway...whether he realizes it or not.

Here's the thing. Stock S2000's aren't slow. They're easily 13 sec cars out of the box. The issue is that to tap into that potential, you will have to wring it out. It doesn't make power in big lazy yawns like EVO's/STi's or large displacement cars.

S2000's aren't "street fast". Bolt ons wont change that.

 

You want to match the diameter of the HFC/test pipe to the diameter of the exhaust to reduce turbulence.

 

I recommended 70mm for both, but OP mentioned he was concerned about drone and noise. I'm sure from OP's diligent homework he found your recommendation posted elsewhere as well.

 

An AEM intake, high flow cat, and proper tune make a pretty gigantic difference. Anything after that is going to be for the weight reduction or just climbing the diminishing returns cliff.

I have this combo with the stock catback and stock header. It works, but the header is mostly for weight. Lowering vtec engagement comes from getting rid of the stock cat and replacing it with a HFC or TP.

 

Shed weight (gutting), 4.56 or 4.77 final drive, single exit exhaust, ap2 ecu or standalone and a tune?

To give you specifics on what brand to get? Why do you think there are soo many threads on this subject?
There are plenty of tuners that designed bolt-ons for this car, each saying *blank* set up guarantees *blank* results over stock.

I can tell you that mine (fujita CAI, stock intake manifold & throttle body, stock exhaust manifold, 70mm invidia TP, 70mm invidia dual exhaust) was a turd on anything but country or highway speed limits (which means the engine has to be wound up, as it is designed, to get what you want out of it).
Go back to stock exhaust and i'm back to pulling harder from a dead stop, but the mid to highs suffer a bit.
This really isn't the best Honda platform for a "bolt-on go-fast-bro" car. There will likely be a trade-off somewhere.

I'm having more fun with the same CAI, stock throttlebody/intake manifold, stock exhaust manifold, testpipe, a 60mm UK mod exhaust, Fortune Auto 510s all around, and some sticky tires on stock wheels.

Minus a few luxuries that were just added weight, too.

 

Bwahahaha. OP couldn't be more "spoon feed me, bitch!".

 

i would probably have to sacrifice some and go with hi-flow cat and dual exhaust still instead of single and test pipe.
i had that on b series and was very shitty freeway driving after 45minutes i couldnt hear anything when i get out of the car

 

Why not just copy/paste using ASM or Toda as the template? That would likely yield the most gains.

 

You can make the power with the stock catback and a HFC.
Probably because there is stuff made in the US that is just as good, or better, for less money.