What we know about speed controls and 3.7 v.
First almost All of the speedos work better with a boosterS and servos are definatly faster.... We have run te novak and the tq boosters. Tq fits better but novak has the cool lights.
Speedos we know to work on 3.7.
Gtb
gtx
some Lrp sphere's. Some will only work for 2 laps some 2 minutes some 8 minutes.
Spektrum works fine.
Futaba fm 75mhz work fine
Jr fm work fine
Require booster or rec pack
LRP spx, Sxx, most spheres
Tekin rs, rs pro,
gearing has been within 1 tooth of 4 cell same combo on most tracks.