is exhaust note changed by number of bends? would a pipe with 0 bends (straight) be louder then one with 2 or 3?

 

I don't believe 0 bends opposed to 3 bends would make much exhaust tone differences.
**not to insult your intelligence see below** wasn't sure if your question was about exhausts in general or straight pipes. ..

The noise level is controlled by the silencer and/or muffler. The silencer if used in a exhaust system is basically a little straight through (you see through both ends)muffler. Same with a staright through muffler - in those mufflers are lil fingers that pull in the flow or noise into the packed canister. There are other mufflers that are not staright through, they has a "S" bend in them. Those are even quieter.
hope that helps..

 

well to be more specific, I was dreaming up a center-exit exhaust and didn't want to do it if it would be too loud, even with a proper resonator / muffler.

 

Nope there will be no difference in volume. There might be a very slight difference in performance if you can keep the pipe perfectly strait.

Just make sure you have a decent sized resonator. Most of the strait-through mufflers these days don't muffle so well.

 

20" + will do the trick