I bought one of these motors the day they came out. It's still sitting in the box next to my brand new mid motor serpent. I need to build my car, work is so dam tiring. The few guys I've seen run the motor say it's faster then d3.5. I've only heard good news about the d4. Sorry to hear the your motor breaking down. I've always had good luck with trinity motors. I fried 2 shuur speed motor last year racing stock buggy.