For the last couple hundred hours I have been using a Flowmaster Hushpower II muffler.  Also used by Tracy and some others I think.  It is done.  The outside held up wery well, but I reciently removed it and discovered that the insides have entirely disientigrated.  Whatever they used as packing has turned to a heavy clay-like substance ratteling around in the bottom.  She steel mesh is in pieces.  I had been thinking that the plane was not as quiet as it seemed 2 years ago..  go figure.

 

So I was thinking about one of the DNA Mufflers someone mentioned.  They seemed nice because there is no packing, just steel dividers.  Unfortunately, it is a little to big around to fit in my current set up.   Instead, I ordered this muffler that also has steel innards but no packing:

 

It is nice because it is going to be smaller and lighter than the flowmaster (or the DNA), as well as less expensive - even the SS version that I ordered.

 

Will report back in 2 years on its performance  :-)