I didn't know that MACs offered more than a few subjects beyond a pre-tuned system for .40-.46's and another for .61's based on TH's listings. Nice to think that I might be able to acquire something that's optimized for this engine size... Instruction sheet specs show bore and stroke of 21.7 and 18.2mm respectively w/ disp of .41c.i.
Hope not too personal: good source for K&B plugs?
I looked at using one of the two holes in the Jett mufflers and looks like drilling/tapping second hole in mounting flange would be right up against other hole, i.e. no edge distance and a "figure 8'ed" hole. Also concerned about volume not optimized in this instance but am ignorant in this regard. Have option to use these mufflers on other subjects as well though.