I just had a 2.25" pipe put on from the cat back and went with the Walker Dynomax Super Turbo (#17747). If I'd talked to the kid doing the actual install, I'd have had him do it from where the two intermediate pipes join all the way back because he was totally on board with elminating the cat and forming the end of the pipe to fit the collector from the mid pipes. Guess I'll take it back and have them do that later.
For now, I'm totally pleased with this muffler. MUCH bigger pipe than stock yet it's quieter than it was before I took it in and has a nice deep tone to it. The old muffler and pipe had sort of a raspy sound to it and much higher pitch.
If there's any power difference at all it's in the 3k-4k RPM range. Don't know if I'm really feeling an improvement or I just *want* to... LOL.
Anyway, just thought I'd put this here in case anyone's thinking about upgrading to a 2.25" pipe and wondering about a great flowing, quiet muffler.