BLADES (and everyone else asking questions about this) - do a search for "sound deadening AND sound damping", there are several threads that have covered this in depth. More Mat isnn't always the answer, and small pieces cut to fit work better than just "sheeting" the surface in question.
I'll do a sticky on this today, I think - I've been meaning to for a LONG time. Sorry, I'm a slacker lately....
