I've gotta disagree with Greg on the firewall insulator for a strict reading of the rules, and the reading I used when I was building my car.

Simplifying, the rule states that A and B can be removed, as can their insulating mechanisms. There is no allowance to remove insulating material that doesn't insulate A or B. The dash is not listed in the list of things that can be removed, so why do you think it's insulator can be removed?