We used Dynamat on our '70 Barracuda convertible, with expanding foam in any crevices / boxed frame rails (including the windshield surround and tight panel gaps where water was known to collect). Made a drastic difference with the overall noise on the car, particularly with closing the doors. However, Dynamat is expensive and a royal PITA to work with.

On two C5 Corvettes (my father's '02 'vert and my previous one a '01 'vert) I used RaamAudio's RAAMmat two-layer setup. The first layer is a (thinner than Dynamat) traditional sticky sound deadening rubber / adhesive with a aluminum foil backing, with a second layer of their adhesive-backed thin foam. Made a huge difference on both vehicles, to the point that I ended up not replacing the stock speakers like I'd planned because of the reduction in road noise and a better sealed environment. The thinner material made it significantly easier to work with than the Dynamat, both in cutting / handling and in pressing into grooves and corners. A small plastic roller worked well for pressing it down. When I get to this point on my '56 I plan on using a combination of spray-on liner (on the exterior) and the RAAMmat products.