I installed kill Matt butyl insulation on the underside of the roof when I removed the headliner. It is 50 mill thick self-adhesive and foil backed. Amazon sells it in a 50 square-foot kit for $59.99. I think I used seven sheets for the roof and will probably do the doors and possibly rear wheel wells if I get motivated to remove interior panels.It would be a good idea to combine the butyl insulation with close cell foam for dampening.