JM's sounds the best to me.
Here's an in car vid of my z pulling away from a light. (partial throttle)
http://album.hybridz.org/data/509/MOV00638.MPG
-MSA POS header
-2.5" MSA turbo (mandrel bends) exhaust and turbo muffler.
I've run the same system without a muffler and although it sounds VERY nice, it is not streetable. (well, maybe to some ricers, but not me.)
edit: oh yeah I have 10.3:1 static compression. I have been told that this tends to change the exhaust note.