Am installing dynamat sound proofing in the trunk area of the car, plus the inner fender areas. My 2013 GT CS has such horrible road noise, that I also sprayed truck bed liner 1/16" thick before applying the dynamat. A simple tap test with the knuckle showed a marked improvement. Now I am working on the inner fenders, first applying the truck bed liner, then adhering the dynamat, also treating both sides of the removable inner fender with the truck bed liner. Super easy to do, and am looking forward to road testing.