i have a 13.5 with sintered rotor not the same power as 4.5 or 5.5 but the ideal is the same , the ? is do you run carpet or asphalt , i find alittle hard to gear my car based on final ratio do to sometimes it doesnt work the same as NOVAK recommeds to gear this motors , i gear my car based on roll out and track size,
the track that race at its not big at all only 70'*40' where rpm isnt to much of a factor but torque takes a mayor part , i have a xray t2 007 us spec and normal gearing on that car is 116spur with pinion starting around 29 or 30 for stock , however with the 13.5 i had to gear the car with 100spur and starting with a 36
pinion depending tire sizes for foams of course ,,, last time i race the car i didnt
change pinion all day with 3 heats and a main and the car was just getting faster every qualifier also keep in mine the motor temp due that sintered rotor let you gear higher than usual also remember that novak brushless do have lots of power but rpms are not as high as a well tuned brushed motor so there for you have to gear higher,,,,, BTW temps on brushless motor are around 140 to 155 of course if it is gear to the moon
hope this little info helps.