RE: Fitting raptor 30 muffler.
Clean the engine exhaust flange and the flange on the muffler. Use a little 5 minute or 15 minute epoxy glue as sealant. Smear some of the epoxy into the threads on the muffler. Tighten bolts hard while epoxy is still wet - but not hard enough to strip out the threads.
Check after first flight.
Fritz