Roof insulation

I am replacing the wiring and headliner in my friends 38 sedan. What would be a good method of insulating the roof under the headliner? My concern would be something heavy lkike Dynamat falling off years down the road and hitting the soft headliner. He lives in a warm/hot climate. I've seen the 3M stuff fail after years of high heat exposure. Anybody have something bullet proof?

Reflectix.

Cheap, lightweight, available at Home Depot and reflects something like 90% according to their claims. Apply it with 3M adhesive spray.

dynamat is expensive, fat mat, noize x and what not...all a lot cheaper and that stuff gets tackier w/ heat so I don't seeif falling off (alu foiled butyl rubber)

I would use RTV to hold it in place, for sure that shit will NEVER let go....

maybe along with the glues in another parallel spot, so when the glue lets go, the RTV is still there holding....

:hunter: