The venturi size would need to be opened up judging from appearances.
Yaro shows pictures of his reworked FORA crank, and he says that improved the lap times considerably
The bearings [according to him] need to changed out to higher quality. So...it makes me wonder if Cyclon, Zalp or Profi use good bearings or not. Yaro noted a difference in lap times with Swiss bearing with the grade 3 tolerance. Tighter than that is no good. Also, the FORA's piston can swell past it's original size and stay like that after it cools down. This comes from a really smoking run on a hot day. The piston either needs to be resized or elsed matched to a worn out liner at that point.
I can see right now that I need to solicit some more opinions. I'm leaning towards Cyclon..but first I'll contact Rich Lopez who writes the CL Combat column for Model Aviation for his advice.