Srt-68 Barracuda

Foiled bubble wrap from Lowe's. For some reason Home Depot does not carry it. As for it's performance, it has given me the same result as the most expensive Dynamat or whatever else is out there. You can do the whole car for $30. Scientifically, a sound wave machine will show better results with Dynamat, and makes for a nice graph to show you why you should spend hundreds of dollars. You can't hear or feel what they're talking about. So save your money.

If, on the other hand, you're building a 10,000 watt stereo system for competition you would be better served with the high dollar stuff. This does not apply to 99.99% of us.