I haven't touched a thing on my exhaust but it sounds like crap. It's a 2.25 from 4-2-1 header to tip. I have a 18" resonator on the straight pipe and a 60 series muffler. At low rpm and cruising it's sounds fine. As soon as I get on the gas it sounds raspy. I did tighten up the rubber hangers at the flange near the flex/straight pipe but nothing else. Can the hangers be too tight ? Not allowing enough movement ? I don't know what to look at first.