Has anyone used any of the Sound Deading Material that is available out there ?

http://www.secondskinaudio.com/vibra...p?category=120

http://www.b-quiet.com/ultimate.html

http://www.amazon.com/s.html/002-758...ntal%20Designs

I just installed a flowmaster and I get the common vibration re-verb on acceleration. I read that some crossfire owners have used these mats to help this problem. Any recommendations ?