Headliner insulation?

Hush Mat worked for me. I used metal tape (hvac) on the seams
so it wouldn't try to peal back when it's real hot. And yes it
worked well in the heat.

Thanks to Redfastback for the tip on the metal tape

http://www.forabodiesonly.com/mopar/showpost.php?p=1020077&postcount=371