Go over to the HAMB and type "peel and seal" , with the parentheses in the search box. All kinds of different solutions come up. This is just one thread
http://www.jalopyjournal.com/forum/t...#post-11505927
I've done two cars with an industrial product, like peel and seal. Heavy rubber, with foil on top. I wouldn't have found it an probably couldn't have afforded it if I didn't have a buddy in the business. Made a huge difference in my 55 bird, and an OT 56 wagon. We put foam carpet mat (cheap stuff from the remnant section) over it and then the carpet. We used a couple sizes of Formica rollers to lay it down. Helped both sound and heat. But you'll see the same results reported from more available products in the link above.