So I replaced my Hushpower II muffler with this stainless steel Moroso muffler:
http://www.moroso.com/catalog/categorydisplay.asp?catcode=35054

I really like that it weighs in at only a little over 3 pounds (vs. almost 10 for the Hushpower).  It is also smaller and more aerodynamic. One down side is that it had to be welded, as it was not the right size to make a slip fit work in my exhaust system (the hushpower had a nice snug slip fit).  The Moroso is essentially identical in OD to my 2.5" OD exhaust pipe.

 To me it sounds a little quieter than the Hushpower after all its insides had burned out, but not as quiet as the Hushpower when it was brand new (I think the packing probably burned up on the first flight so soon thereafter).   I have been flying with the burned out hushpower for so long I just got used to it.

The only place I have flown so far with the Moroso is it to an EAA meeting.  One guy really commented on how quiet it was, which is not a comment I get very often.  So that is one data point.

The innards held up perfectly well the the 1 hour flight.  I plan to fly a few more hours tomorrow.  Will keep let everyone know if it ever gives up the ghost.

--
David Leonard

Turbo Rotary RV-6 N4VY
http://N4VY.RotaryRoster.net
http://RotaryRoster.netrst