[sick472]

Sound deadening mat like that is very good at reducing sheet metal vibrations. Think about adding a piece of chewed bubble gum to the surface of a drum set cymbal...it will kill the sound. It does little to absorb free sound like carpet would. With that said, a piece of sound mat added in the center of the larger open areas will yield the bulk majority of the results. This has never stopped me from adding it pretty much from corner to corner in the cabs. But, for door inners, I'd keep it to a minimum. Inside the lower inner door panel is the first place to add it due to the vibrations from the speakers and then, maybe, to the lower section of the outer door skin. I advise the lower section only...You can imagine what would happen on a real hot day and the mat decides to let go and goo into your window mechanisms. Maybe the Kilmat brand is not prone to this as I have always used the poor-man's sound mat...Peel & Seal Roofing. At any rate, full coverage in your doors is not necessary, or anywhere else for that matter. I did cover the entire floor and firewall of my 72, because it's addicting to put down and just looks so cool...I hope I never have to take it up! lol