I had truck bedliner sprayed into the trunk and trunk lid of my '63 Buick. After that I put down Dynamat throughout the entire vehicle. I knew the guy that did the bedliner, and he charged me $100 (USD). But I had to do all the prep work. Next summer I plan on taking out all the interior (Dynamat and all) including the door panels, windows, etc. and have the bedliner sprayed into it. It will add probably another 100 lbs. or so onto the vehicle, but I doubt if I'll have any problems with road noise, or rust. Next up will be disc brakes all the way around.