Thanks for the help. Problem is, we are limited to a bushing .40 on our club pylon planes, and these seem to be the best choice. Uh, actually I'm just doing research to see if any of the other guys may be cheating, being they are supposed to be stock, baffle removed in exhaust is the only thing we can do. (that will be my excuse if any of the guys see this!) So, aftermarket mufflers, are out, I don't know if they would allow bigger carbs or not.