Yeah, the instructions say 65-70% Nitro...and prop it for "at least 20,000 r.p.m. while still in a fast 4 cycle"
for the break-in...
Mine says "Series 75" on the box, and it has a 0004269 serial # so it might be an early one? I think mine does have a small hole in the sleeve just below the exh. port. (don't remember ) I'll have to check...
I know the guys who pylon raced 'em used the mini pipe. (right?) It's just a piece of seamless alum. tubing about 4" long, and even still has the manuf. red stencil letters on it...