Here are some pix of the muffler install. The first shows the muffler before I pulled it off to check the exhaust port. the second shows the two mating surfaces. It looks to me like the film of sealant is so thin as to be almost transparent, except where it oozed out to make the "bead". I have used the Permatex Ultracopper but did not see much difference in the consisitency or result. I have gotten a lot out of this discussion, especially the idea of using so little of the sealant. Much less than I would have used before. I'm going to redo the muffler again, and use less sealant (Permatex Copper this time). Thanks to all.
Sam