My mate had a 7700 in his xx4...it was an overkill...the motor is really too fast and powerful, it caused a couple of screws to fall off and the whole car to rattle . After 4 packs, the diff outdrives were worn out. He later transferred the motor to his touring car, the same thing happened. I emailed Joe Ford of Castle Creations and he highly recommended the 5700. He said it's the most versatile motor, it works the best for buggies. It is fast, lots of torque, controllable and the it has more gearing choices too. Best of all, it will not kill your buggy's drivetrain mate...Cheers
