I have ran alot of brushless motors from novak 3.5 to 13.5 . The fastest motor I have ever ran on 2s is the lehner 5300 . I think the ratings on some of these motors are bull. The best way to tell if your pulling too many amps is battery temps. If the battery is getting hot (over 120 degrees) you need a battery capable of more amps. The sensorless motors can be geared alot harder than the sensored motors . Temps will tell you if the gearing is right on motor and battery and speedo.