hmmm, my exhaust is a 3 inch straight through, i do have a cat, but, let's just say my muffler is only for looks... :P as in, i don't have a real one, it's just metal made up to look like one, and it's quiet as, maybe because i don't thrash it, if you're worried about the noise, see what you can do to silence it, but don't get rid of the tanabe exhaust, that's so sad