ORIGINAL: proptop

Link...I picked up a few r.p.m. by rolling the lower lip of the ports on the outside of the sleeve.
I don't think aircraft engines turn enough r.p.m. to make all the other mods typically done to r/c cars engines worth while?

The tuned pipe will give ya a boost in top end at the expense of throttlability through the mid range, so it's a bad choice for 3D style flying.
I tried it a couple of times with 2 different .46's and pipes went back to a Tower/Aquacraft muffler.

Any good quality 10% nitro fuel w/ maybe a few oz. of extra Castor mixed in will work...and mine likes an O.S. #8 plug...and maybe you could use an 11 X 7 for break-in before going to the 13 X 4W for flying.