ORIGINAL: tkg
This is hard to explain but its simple once you figure it out.
Drill a 5/16 hole down through the fins from the top to bottom. One hole on each side of the exhaust port. Take a 5/16 rod and drill n tap it through the side 8/32.
Slide the rod in until the taped hole is lined up on the exhaust and then use a long bolt to screw the muffler on.
Your making a T bolt arrangement.
I have a couple of these kits from TKG and they were nice, but eventually decided to just use the springs. I made my own straps to use the springs with the welded up aluminum mufflers