I have run a GRP .21 tuned version in an 8T for the last race season with very little problems. I did notice a little lack of torque in the heavy truggy but I upped the spring rate in the clutch and went to a long header to max out the torque and was pleased with it. I have recently purchased a powerhouse race modded GRP .21 non tuned and this motor smokes the tuned version in performance and mileage. I average 11.5 min per tank which is +1 min longer than the tuned version and I don’t see any issue with not enough torque. I did switch to an 8T 2.0 and even used the stock spring setup of gold and green which is much weaker than the all silver spring setup I was running before. I will have to see if it lasts like the tuned version. I had 6-6.7 gal on the tuned version and it was still running strong. I replaced a front bearing at 5 gal and that’s it. I have sold the tuned version so no more comparison but I am sending a new GRP .21 tuned version to powerhouse for their turbo mod. I am sure I will be happy with it. I have run an OS V-spec and it did not make it past the 5 gal mark. The compression was gone and the front bearing was gone too. Tune was not difficult just don’t touch the middle needle ever. If you do you will wish you never did, there is no going back after you touch the middle needle. GRP gets my vote I will prob buy a 4th.