I picked up a used 1/3 Pitts special with a Moki 2.10 installed. I Experimented with several props and settled on the Vess 20B for best performance pulling that 20lb Bi-plane through big loops with smoke on! The APC 20x8 turned 7,900 but had less pull in vertical maneuvers, Menz 20x8 turned 6600, and plane lost speed and thrust, Master airscrew 20x6 wood turned 7,300 and flew the Pitts quite well! The Vess 20A turned 7400 and performed similar to the master airscrew. The Vess 20B turned 7200 and has the extra pull needed to haul that high drag airframe through nice big lazy loops, straight up into nice hammerhead stalls, inverted into outside loops etc.... I run S&W 2% nitro, and 15% oil comprised of 1/2 synthetic, and 1/2 castor. Engine head is around 170 deg F. after a 8 minute full throttle aerobatic flight routine. The low end carb adustment disc is 1/16 counter clockwise (rich) of the detent mark.