I need convincing
Im' running the 91FX on a Calypso. With a standard muffler it turns a 13/10 APC 10200 and a 13/8 3 blade Master at 10400 tuned for flight. With a Ultrathrust muffler it turns the 13/10 at 10800 and the 13/8 3 blade Master at 11400, again tuned for flight. This is on 15% nitro.