That engines peak power is at 29,500rpm and a max rpm of 32,000 according to the spec list. These kinds of engines need to rev to make good power. My lapped Enya .30 turns a 9x5 APC at close to 16k open exhaust and 5% nitro 25% castor fuel. I'd bet an 8x5-8x7 would get it really singing. But what do I know.