OS .91FX with stock and Performance Specialties mufflers
 

OS .91FX rpm
Location: Shalimar, Florida, on the north gulf coast
Temp: high 80's
Humidity: Very humid, just after Isadore
Fuel Omega 15%
The Performance Specialties muffler is the long chambered muffler for large props on the .91. The short chambered one is tuned for the 12-8 and 13-6 props.

Prop Stock Performance Specialties
Muffler Tuned Muffler
14-6 Master Airscrew 10,600 11,500
14-6 APC 11,100 12,000
14-6 Top Flite wood 10,600 11,500

A solid 900 rpm gain on all props.