RE: Super Sportster twin...
Ouch! Sorry to hear about your mishap. But glad to hear that you will repair it.
I use red (high temp) silicon sealer on all of the muffler joints including the muffler to engine joint, the mid-muffler joint(s) and both ends of the long bolt. Haven't had a muffler loosen up or leak in the ten years I've been using it.
Jim