i'm thinkin of either buy a set of headers or a throttle body which would be better power wise

 

Header ftw!!

What else do you have done? I would get an intake and a cat-back first if you don't have those already.

 

But if you plan to go turbo the header would be a waste so make sure the stuff you buy now will still be useful if you plan to do any more modding. If you are gonna go N/A then the header, exhaust, and intake would be a really good start. Your not really gonna get too much HP from a bigger TB.