If you dont have to run a roar approved motor I high suggest you dont. The outlawed spec 17.5 and 21.5 motors are noticeable faster as well as cheeper than any roar approved motor. I love my trinity 17.5 punisher and it’s way faster than my roar legal hobbywing g4 or my r1 wurks v21s or and my new reedy sp5 17.5 motor. Hobbywing and fantom also sell outlaw spec 17.5 and 21.5 motors.