I've had good success using R-Blox, an adhesive backed Dynamat like material. A roll of Dynamat was over $300, the Rblox was $89. for a similar sized roll. The stuff works wonders, just cut to size, you can cut it with scissors to a sheet or strips or patches or any shape, peel the backing and stick it on. Best to be done on a warm/hot day as it is eaier to work with. Much easier to control and apply than foam. It is heavy though, it took me about 6lbs per door to do the last car that recieved the treatment. A large roll weighs in at 40lbs. Search Ebay for Dynamat and R-blox and you'll see the price difference.

Alan