Muffler to manifold

[Tom maxwell]

GuysI am struggling to get a good connection between the muffler and the exhaust manifold
. In the past I have tried some of the ideas in the catalogs.
Between Bert's, Snyders, Brattons, and Macs , there are a lot of ideas on how to make this connection leak free.
Before I take this apart one more time, I would like to know what is the best trick.
With just the clamp , I have leaks. The manifold and muffler I believe are in good shape and round
Thanks
Tom