@Michael McKelvey wrote: "At the connection between the muffler and the collector, I am using Permatex Ultra Copper Maximum Temperature RTV Silicone Gasket Maker. "
OK, so I know that Tiger recommends using this stuff, and I know from personal experience that it works in higher temp applications, but the exhaust heat is going to cook the RTV over time, petrifying it and making it a real bear to clean up the flanges the next time. But you already know this. Besides, that RTV is designed for use with gaskets. There is a different version (410? 510? I can't remember) that is specifically made for metal flanges (It's called a "Flange Sealant") but with lower temps.
It would be much easier to take the muffler pipe with the flange on it to a NAPA store and ask for an exhaust gasket to fit the flange. I'm thinking of the metalized composite style gasket which they may have all made up, OR they also sell the stuff in bulk sheets 12" X 24" or so and you can cut out your own (be aware that cutting this stuff can be difficult at home).
That's all I've got, Mike.