I think this whole rice burner thing is just for the 600 motors. Or maybe just autos. My buddies 05 auto sounds pretty good, but not nearly as good as my 03. If I can figure out how, I have a video of me on a dyno and it really doesn't do justice to the deepness of the sound unless you have a decent sound setup. We had the computer plugged into the tv to watch the vids and it is hooked to the stereo and I was amazed at how well the low, deep sound of the exhaust recorded! I got alot of compliments at May Madness on the sound of the exhaust. BTW, mine has nothing in it but pipe and the Aeroturbine. No cat, no muff, no resonator tip, nuthin. LOVE IT!
Also, if you put a 5" tip on it it *may* possibly help deepen out the sound and clean it up. It did on mine. Also, there are resonator tips available. Worst case, install a muff after it but don't take it out. I would definetly kep it in there if it was me, muff or not.