Andy T... The STS D3R is an ok motor and not bad when ran on a short track, but when ran on a large track there's a good chance of the crank breaking... I've had both the 3 port and 5 port STS motors... Both cranks cracked in the place as well... and they were the new super harden cranks... And no, both STS motors can't touch the new OS TZ-3P nor the Sirio EVO III in speed and power. Remember the key to engine performance is proper engine breakin and matching it with the right tune pipe...