Hey FMX---I just used the home depot stuff inside my model A roadster pickup doors. I goes on really nice, and it certainly deadens the "tinny" sound of a metal door. The only concern I have is how well it will stay on a vertical surface. It is made to lay with the tar side down on a roof. I just wonder if after a day parked in the hot sun I will have all this stuff slumped into the bottom of my doors. I hope not.