Jim,

Even if the seal isn't perfect between the exhaust stack and the muffler, the amount of pressure you'd lose isn't enough to matter. About the only benefit of the gasket is that it prevents the accumulation of unattractive black residue on the outside of the muffler.

The brass gasket that we use on the high-rpm Nelson and Jett engines is for another purpose, namely, to prevent heat and vibration from causing tiny spot welds ("galling," pardon the expression!) between the two aluminum faces. Other than that, I wouldn't bother. The TTs and STs both work fine without any sort of gasket.

OK, now I'm up to .04 ... when I hit .25, I'll tape a quarter to the wingtip!

Duane Gall
RCPRO