I'm looking to upgrade my exhaust system, but I want to keep it as quiet as possible. I understand that quiet = backpressure, but here is what I'm considering. I have a 98 ITR with a jrsc. If I get a Kamikazee header (2.5) into 3" piping and remove the cat, then what is the quietest muffler I can run it into and still get significant power gains? How much louder would it be with the test pipe and the stock US ITR muffler?