Guys,
I need a recommendation on material for a metal muffler to case that will seal yet allow some cushioning so as to not be to tight to distort the case. I have tried some thin aluminum but that needed really cranking down on the bolts. I'd really like something a little softer. Any suggestions?

Best,   DennisT 

  If one really must use a gasket, use sopme gasket material meant for the cylinders of motorcycle engines for base gaskets. It will crush a little bit and seal but may help prevent vibrating loose like soft metal will. Copper sheet will also work but offer the same issue as aluminum. filing the mating surfaces flat and sealing with hi temp sealant is the easiest way.
  Type atyou later,
  Dan McEntee

I found some of the old Perfect gasket material (the green paper like stuff) that was still soft and just the right size for covering the exhaust area. I made up the gasket leaving a little extra material on the inside and outside edges (I know this may restrict the flow a little but not much). I was able to then mount the muffler carefully tighting it down with the glow plug removed checking that I didn't tighten one side to much and cause biding (Fox 35 thin case). I also added some blue lock tight on the bolt threads to prevent losening.

Best,   DennisT