OK, so i just found on wiki that the voltage used times by the KV rating gives the revs that the motor will turn to. Higher KV, higher motor speed.
Thing is not all the motor manufactures list the KV or rev limit to their motors so I don't know how to compare the Reedy ones to other motors.
Is a 6100KV motor like a 5.5 or a 7.5? Grrrrr
Anyone