this car is basically completely built all-motor, right from the factory. i'd probably put a short-ram on just because i like hearing the secondaries open up, and throttle response for downshifts is a HAIR better, but don't think you can top the honda engineers by reading a parts catalog. i agree with gearing, weight savings, and suspension. there's a fully pimped used 05 at my work and it's got everything i can think of. the sound is killer, barely different from stock, he shaved weight, but acceleration-wise, i can hardly tell.