The one of the best exhaust you can buy for S2K AP1 F20C 
MP http://link.marktplaats.nl/498238622
Pics http://www.gotuning.com/product_info.php?products_id=1009
Vids:
OUTSIDE
http://youtu.be/T6LxYZokg5w
INSIDE
http://youtu.be/gNvI737W54Y
Dyno:
http://blog.gotuning.com/2010/…nda-tuning-press-release/
Description:
Fits all S2000 model years. Stainless Steel Construction with Burnt Tip. Made in Japan.
70mm to dual 60mm piping, dual mufflers, 102mm tip.
Power gains of 10.9 hp at 8001rpm and 6.9 lb-ft at 6256rpm.
Go Tuning Unlimited worked with Greddy to develop an exhaust to our specifications. Designed to have a refined look that makes power without sacrificing sound levels. The result is a very quiet exhaust that is 94 db @ 6000rpm (stock is 92db). The 70mm to dual 60mm piping was able to produce power gains of 10.9 hp at 8001rpm and 6.9 lb-ft at 6256rpm. The construction is entirely stainless steel with a torched tip. The exhaust fits very well on both AP1 and AP2 bumpers where most exhausts either stick out too much on AP1 bumpers or are too recessed on AP2 bumpers.
Today’s sophisticated tuners want it all, and GReddy’s SE exhaust systems deliver the full spectrum of features desired in a street performance system. SE exhausts increase flow via tuned piping and larger, free-flowing mufflers for improved power, but provide discreet sound levels that won’t attract the wrong kind of attention. The exhaust note is comfortable and sporty, not loud. Each application is tested and tuned for USA spec. vehicles, so fitment and sound is confirmed. All SE Exhaust are test to be well below the 95dBA standard. The new smaller Spectrum exhaust tip(s) help disguise the system from the rear of the vehicle, but reveal show-quality appearance from the side and underneath. Whether you are cruising down the road or at wide-open throttle down the track, the Spectrum Elite is ready. Refined sound. Hard-hitting power. Superb looks. Excellent fitment. GReddy quality. - A true Sports Exhaust