I’m going to cheat a little on the concours route to improve the under layment that was originally put in from the factory because you’ll never see it and it will improve the noise level and hopefully the heat level of the car. Since it is a 428 Super Cobra Jet, it has a 3.91:1 rear end so it will turn some RPM at road speeds.
Quiet Ride has an entire car kit which I ordered, knowing I wouldn’t get to use every piece. Some of it would be visible, so I’ll only use what I know is hidden. These cars originally had some insulation as you can see in the next picture.
The original carpet underlayment was a tar paper like material and it was pretty gooey. The strips are sound deadener which go under the heat sheild.