RoVey_1

It will add noise. No power to be gained that you will notice. 

Would probably be a few hundred bucks for a mechanic to change headers. Its pretty straight forward and a good starting point to learn how to work on your own car though

yea ill see because i dont want to go to the trouble of doing the exhuast if it wont be significantly louder, looks pretty straight forward and should be pretty easy with a boxer aye 

There arent any. Getting power out of an NA subaru is pretty much pointless. They just done make power I hate to say. 

As for the exhaust stick to a 2.25". A 3" will make it sound like a wet fart and lose precious back pressure (or whatever it is that makes an NA exhaust work) so youll make things worse. 

Might want to look into some Un equal length headers too. Theyre what make the subaru noise. NA EJ with stock headers sound pretty bland

Yea i thought that would might be the case. You reckon a 2.25" will make much of a significant improvement from stock? How much do headers cost if a mechanic does it?