I fly my CG Ultimate with 91FX, 15x6, sea level, 10% nitro 18% oil, fuel pumped, I have tested 13x8, 14x8 & 15x5; so far I like 15x6 the best; rich engine, ultimate aluminum spinner, slim pitts muffler.

I believe the secret to enjoy this particular plane is to keep it light, I have seen it flying with 120 4-s and with 75 2-s I like my combo better so far.

I do have a SAITO 100 ready to intall in a finished MIdwest mini CAP232, however being my Ultimate close to general maintanace day I may try the SAito 100!

If you go with the FX and bigger prop, you need to open your cowling more than normal and have your engine on the rich side, so no over heating happens o.k.