Previously, I had purchased 2 of Duane's GT50 R motors.....unfortunately, I had to send both of them back as I had numerous issues with head sealing. The head bolts would loosen up and eventually both motors were more trouble then I was willing to put up with. Through all this Duane couldn't have been nicer or more professional and as a goodwill gesture, he sent me a newer version of the motor to try out at no cost to me. This new motor has a one piece head design that totally eliminates the head bolts and so far- I've been loving it. According to Duane, this is a slightly less powerful motor then the GT 50 R, but if it is......It's a really small difference. The motor had a really nice torque curve-from right off idle up to 3/4 throttle-it feels exactly the same as the GT 50 with the power tailing off a little earlier the older version of the motor. As it sits, I changed out the jet to a larger .80 part and am running Opti 2 at about a 30/1 ratio for a few tanks. I want this motor to last for awhile and the last thing I want to do is run it too lean and burn a hole in the piston. Here's a pic showing the new head design.