i will see if i can find it on tower. St made a Q500 muffler its tuning is very close to the Jett black/Q40 muffler. much cheaper though but they didnt last more than 30-40 gallons and then would fall apart. The jett mufflers seem to be good for 50 or gallons on normal runs. if get them hot then much shorter time.

here is the link on Tower's site.
http://www3.towerhobbies.com/cgi-bin...?&I=LXFW05&P=7