Not the final word, but I tried SS Swarf in one of my muffler experiments
and while it withstood the heat, I found that after several flights the
pulses had hammered it into small lengths and blew most of it out the tail
pipe.  Inconel might be able to with stand the pulses.

Ed

Or, perhaps the stainless perforated tube within another tube. Or even three layers of tubes within a tube. Over half of the battle is getting the exhaust pulse below supersonic.

 

One of the math majors could work out the spacing between the tubes. The perf tube does hold up just fine. There is no packing in my muffler.

 

 

Lynn E. Hanover