The OPS line of motors are very impressive. I have been testing the OPS Speedster for a few months, and it's a very nice motor.
The OPS Torque is by far the best motor from OPS though. Great milage with the OPS pipe, and very smooth. Chris Crews has been running the '06 series Torque motors, and his only complaint is longevity- 3 or 4 gallons at the max.