Now that I think about it, you might want to check out:
www.f-bodyhideout.com/videos.htm
Note in the video section it has a file "seth.mpg" I believe it is, it shows stock SLP exhuast (I believe) and a before/after LT switch. Like the sound? So do I.
Well now check out any of "Gonzo's" videos, with Project Speedy. The file with a good exhaust clip should be QTECdemo.mpg or something, I've changed the filenames since I DLed, but note both sounds, Speedy has a much more brutal sound, which I personally don't care for, but to each their own.