well if you go to lets say towerhobby and you look at a motor lets say this one http://www3.towerhobbies.com/cgi-bin...&I=LXWLX0&P=ML

NOTES FROM OUR TECH DEPARTMENT (Located at the bottom of the page)

This is the Havoc Spec Brushless Sensored ESC and 17.5T Motor System
from Novak.
17.5T system specifically designed for vintage Trans-Am racing and
is approved for ROAR spec brushless racing.

FEATURES: Meets ROAR specifications
Rebuildable 540 size motor equipped with sintered rotor for precise
throttle response and high temperature resistance, motor also has
shielded sensor cable


also that link is just for reference im not a novak fan always been a mamba fan while my friend is a novak junkie. plus it will depend on what your going to do with it but if your going to bash id stick the fastest i could get in the truck but if your going to race i dont know race rules or what motors to use for racing so i couldnt help you there. i strictly bash more fun in my eyes.