[Turk]

TC,
In Summit catalog there is an assortmnet of heat shield material. I believe the brand name is Thermo Shield. They have different grades, 2000 degree mat being the best they offer.
While you are at it make sure to acquire some of the adhesive backed tape made out of the same material. It makes a very good trim and splicing material.

I believe Aircraft Spruce Catalog may have some more exotic stuff.
I can't overemphasize the virtues of insulation in the alloy car.

You may also consider venting the fender liners right ahead of the headers like ERA does.

TURK