Didn't realize that this topic would generate such a wide range of comments when I made the initial post. The ST "economy" muffler mentioned in a early post looks very interesting and I will replace mine with one when I lose another expansion chamber. Although not all posters agreed with my dislike of the ST muffler, most seemed to agree. ST can improve their product in my opinion by going to a more typical "OS" type muffler. Thanks for the large number of helpful responses.

Mike H.