i see some people using 2 inch to the intercooler then out of it to the throttle body they use 2.5 or 2.75. whats up with that? im just trying to maximize my power and efficiency.

i know that may help it spool faster, but will it drop off cause it cant flow after XXX rpm and XXX pressure?

 

If you're gonna stick with a stock motor, then go 2" all the way around. You won't have enough power to warrant the 2.5-3", and staying with one size doesn't require you to buy 2 kits, or buy pipes individually.

 

Agreed unless you are putting on a big bodied turbo 2 in is all you really need for a 2.0l car. now if you step up to say a g30 garrett or equivalent then 2.5 all around.

 

^ totally agree with daytonmvp23^