I recently ran into another case where someone sealed exhaust gaskets
with red high temperature RTV silicon sealant. I don't know off hand
what the temperature rating is for RTV but it has to be way lower than
what the exhaust flange sees. I will say the flanges and gaskets (the
thick spirotalic no blo style) were not leaking. Am I right in
thinking the lack of leakage is due more to the gaskets working as
required than the RTV?

John Dupre'