Use oem gaskets on headers
Hey all, this is just for anyone who finds this thread searching for information on gaskets. I recently put long-tube headers on my Mustang, and I ordered Percy's carbon on steel header gaskets; I was told these were the best non-metal gaskets you could get.
Well, these things blew out immediately, as you can see in the picture I have attached to this post. The exhaust leak was loud and obnoxious. Replaced with Motocraft metal gaskets and the problem disappeared.
As an aside, why are companies allowed to false advertise? How can you sell something en masse that simply doesn't work? There should be a way to sue over that! But since I can't, I'll just try to warn others.
I also changed my water pump using the gasket which came with the new pump. Has been slowly leaking ever since. Will be replacing with an OEM gasket when I have a chance to tear everything down again. Moral of the story (and something that I have found applies to parts, not just gaskets); whenever possible, go with Motorcraft or Ford racing.