Best heat insulation?

Hi guys,
I've been tuning the cuda today.
I've got fenderwell headers and the heat coming from them is incredible. I have wrapped the headers but the floor and the fenders are getting really hot.
All my temps, timing and pressures are normal.
What is the best heat insulation you guys are using. I need to run some on the floor up to the firewall and on the inside of both front fenders.
I've been looking at dynamat, but it seems it's more of an acoustic dampner than a heat insulator.