HP

[TooFast]

If I were to get a full exhust system w/ headers would that produce more power rather then getting just an exhust system and no headers?

[tg]

Steak Sauce

To reply to your question: downpipes make the biggest difference (assuming you have a turbo...).

[nsrZ32]

Assuming you have an NA since you asked about headers, you will see more of a gain with aftermarket headers and an aftermarket exhaust than you will just just merely a catback exhaust.

On a twin turbo car, you will benefit greatly from manifolds, downpipes, testpipes, and catback. Although aftermarket manifolds are not necessary as you can make a TON of power on stock ones.