1. OPEN EXHAUST:
APC 13x10 gives 10750 rpm, Static thurst = 5.7kg
G-Sonic 13x10 gives 11300 rpm. Static thurst = 6.4kg
2. RESONANCE PIPE(Macs) after being tuned for each(!) propeller:
APC 13x10 gives 11200 rpm. Static thurst = 6.2kg
G-Sonic 13x10 gives 12050 rpm. Static thurst = 7.15kg
The difference between the engines was in the range of less
than 50 rpm on the same propeller and varied while
playing with the carb needle to get to the max RPM possible.
The flight tests were done on a another, older .91FX and
the speed and climb were confirmed also by some other
guys (APC-adicted) to be very obviously in favor of G-Sonic.