[AndrewJ]

I know I saw someone here do a coroplast bellypan with aluminum flashing over the exhaust tunnel, seems like the way to go.

OTOH, my coroplast on my (partial) front bellypan isn't looking too shabby for being a mere 1-1.5" away from the exhaust header. I'm beginning to think the whole exhaust heat thing is overblown.

But then again, my car's cat converter is right under the header. I'm sure if your cat is under the car you'll won't want coroplast anywhere near it.