Well when i rippeed out my interrior i decided to put down a sound deadener material but did not want the price of dynamat... I went with an alternative called B-quiet which at the time was a lot cheaper then dynamat and still appears to be, I poked around the dynamat website and found it to be expensive still...
This link is the same place on ebay where I got mine and was able to cover my car well with this amount including the trunk.

http://cgi.ebay.com/Ultimate-B-Quiet...QQcmdZViewItem

So here are a few pics of mine deadened and it sounds great I have a couple of videos posted in my sig and in one I am sitting in the car with it being reved and you can hear a huge difference when I get out...

 

James-- Does ur deadener provide heat insulation? I'm looking more for keeping the heat out instead of sound, as I have a vert

 

I used it in my 70 convertible. Helped with noise and seemed to help with the heat issue. I also did the inside floor pans with the rust protective paint, didnt want to take chances being a convertible I figured she needed all the help she could get.