3" certainly will not hurt a thing, I have never lost power going bigger. It will kill a bit of bottom end/take off on the street but if you got good gears it will not be as noticeable as tall gears. The best part is you will have room to grow as the urge to use more nitrous takes hold of you lol. As far as sound there is truth to what jpar is saying but as you stated allot of it is in the mufflers. Its all about air flow, bigger cubes or smaller cubes with compression will make more sound simply put. if you want a crackling exhaust have good overlap and cylinder pressure and it will sound as good as possible regardless of the pipes. if you really want a simple cheap solution for less noise but the open headers sound get some car chemistry inserts and just run a set of 3" collector extensions.
