Muffler to header joint seems stuck

[GleepGlop]

Is there any trick to separating the muffler and header pipes? I've removed the clamp, everything is loose except where these two pipes meet. The gasket seems like it's welded the two pieces together.

[scrambler]

The muffler and header are often very difficult to separate. First, you need good old friend rust remover spray, which you spray and let work. Then, remove the header nuts and the three upper muffler bolts. The lower bolt is only loosened, not removed. Then you can wiggle the muffler until the connection comes free. Spray more rust remover spray, wiggle more, and eventually, the header will separate. The gasket can be reused. New gaskets fit very tightly, making it difficult to push the muffler all the way open.

[GleepGlop]

Thanks for the heads up about the gasket, I was planning to destroy the gasket if necessary to get it off, but I'll avoid that now. I haven't had time to take another crack at it but I'm going to try to loosen the muffler bolts, keep the header bolted, and find something to hammer out the outer muffler ring, sort of like hammering in a bushing with a socket.
Why only loosen the bottom left bolt? I've already removed all 4, but I'm curious about that one.

[scrambler]

Why only loosen the bottom left bolt? I've already removed all 4, but I'm curious about that one.

It's easier to pull on the header, so you have to leave the muffler attached at one point. Using a sledgehammer will just dent the thin muffler sheet metal. You definitely need penetrating oil and a lot of patience; if you wiggle and shake it long enough, the connection will loosen.