This could just as easily be posted on Carrier, Scale, Stunt, or Combat, but you asked it here, so here goes.....
This setup has survived several bench runs and three flights.
It:
Reduces the noise level.
Make the engine idle better.
Satisfies F2d rules with it's 8 mm oraface.
Materials: 1" square tubing from Home Depot, Permatex hi temp gasket sealer from Pep Boys, silicone sheet from McMaster (not really needed), 1.5" 4/40 bolts.
ps: This not my entry in the muffler and test stand beauty contest.