My club races Sky Raiders with OS .46 AX's and lost mufflers have been a common theme. For this year the rules have been changed to allow the use of the Macs one piece muffler to alleviate this problem.

http://www2.towerhobbies.com/cgi-bin...p?&I=LXZ652&P=

Ken -

Another problem the OS mufflers have experienced is the muffler loosening up from the engine. When you safety wire the back half of the muffler to the front, it doesn't hurt to wire the front half to the cylinder at the same time. I've seen more than one OS muffler retained this way.

Hogflyer