Gary, I would also suggest sealing up the muffler with high temp ATV or JB weld at the seam and the bolt head/nut area to avoid any pressure leaks. This will help it stay together (
especially the JB weld!
) and improve the RPM's a little bit too. I also like using the brass muffler washers between the engine & the muffler to make sure it seals tight.
Scott Smith