You can use Dyno matt,E dead or Fat matt depending on what you would like to spend.
http://www.fatmat.com/
http://www.edesignaudio.com/index.php?cPath=1_24
I guess you can get 100 sq ft self adhesive fat matt off ebay for around $100 shipped. I plan to do everything possible to get rid of noise and rattles. inside/outside door skin...cab, inner fire wall, floor and behind gas tank if I can get to it. (My truck needs to shed alot of Db's...lol)
