Propellers that I used are in accordance with the rules.
Aces combat rules determine the prop size, muffler measurements and ground max rpm.
My best os.25fx with hatori muffler apc 9x5 prop 15% nitro rews 15900rpm.
And idont believe that enya.30 can done 16k never ever, .25bb alcrome rews low 14k with apc 9x5 prop and enya special muffler.