To me, R-Spec II motor (over 4.0 ) is now one of the fastest motor, about same ranking with Perfection King 4.2, King Pro 4.2. The motor is clearly faster and stronger than the "pink "3.8 ", faster than Perfection 3.8.
The motor does need a strong car such as Bit Char-G booster, Microsizer Booster, or MOSFET mod cars to fully show its speed and torque. Even the original Bit Char-G Special Edition board does not supply enough current to drive this motor.
That is the motor to own to prepare for the toughest race, either lap or straight away.