go thru s2ki forum, there is a list of different intakes and exhaust and all the other parts and review.

http://www.s2ki.com/s2000/topic/8225...-thread-links/

intake: i would recommand KnN
header: Js racing
exhaust: Js looks good, i think single exhaust is better because its lighter

the best thing you can do is 4.7 final drive.