I too had the problem of blown out exhaust gaskets. I have bought intake, and exhaust gaskets from every seller on the internet and they all SUCK! They are cheap and inferior and have ALL FAILED on me! The aluminum one that needs sealing also!! The oil in the gas mix just pushes past the RTV sealant after a few miles of hard running. I also tried using permatex aircraft grade gasket sealant on them and it didnt work. I would have been better off buying a bag full of the cheap paper/rag gaskets. I got tired of changing a gasket every 10 miles and cleaning the mess off my bike and engine. I started by stoning the mating surface of the muffler perfectly flat using a whetstone and trans fluid. Then I cut out a new gasket from an old ford straight 6 4.9L intake/exhaust (single gasket coated grey) self sealing gasket I had. This Ford straight 6 engine, combination intake/exhaust gasket has a steel core and is coated with a heat activated sealing substance that seals when you run the engine. Its about 2mm thick I have not had a blowout, or oil leak from my exhaust port since I installed it 800 miles ago! It took more time to seal because the bike engine exhaust doesn't get as hot as a ford exhaust, but seal it did. I figured if its good enough for my ford well.....I did have a little trouble cutting through the gaskets steel. I didnt have tin snips so I used a hole punch set and heavy scissors. No more leaks for me.