There made from a carbon material so it can't burn through and there extra thick and they crush down and fill any imperfections and there guaranteed, go to napa and check them out. Don (or go to there web site)
My exhaust guy always used steel donuts between the header and collector. They seal perfectly and come back apart easy and are reuseable.
Do any of these gaskets have larger openings? The exhaust ports on my new Dart heads and the Doug Thorley shorties are both significantly larger than the openings in the gaskets I was about to install.
I ended up with a set of Mr Gasket laminated dead soft aluminum gaskets. I got them cheap at the swap meet at the Emerald Coast Cruize a couple of weeks ago. Looks like they are gonna do the trick.
Got some of the Remflex as some of the guys here suggested, swore like a sailor getting them on but they have been on for 3 weeks and not even a hint of a leak