i run OS#8 or OS A3 depending on the weather & 16% nitro. more nitro will shorten the life of your engine, but you will probably destroy it some other way before the nitro will kill it anyway.

the 4 shoe clutch flywheel is considerably smaller than the stock one making a starter box difficult to use unless it has a small wheel that will reach the flywheel. i still use the pullstart, but i can usually start it 2nd or 3rd pull once it's primed.