I have had the following in my truggies - P5, Vspec, 21-5Kt, Max power M5, Ninja, and GRP 21 - all are good, but the GRP is my favorite..more then enough power for any track, 10 minute run times, low temps, and will last. The Vspecs are great for the money, but I have not had one last very long. The P5 is a solid all around motor, but there are much faster motors out there. The 21-5kt is the most finicky thing I have ever run, and I would not recommend one...in fact, I am getting another GRP to relegate my 21-5kt to the backup's backup. Speed's are good too, but I have not been pulled by a Speed with the GRP in the truck, and there is a good bit of price difference between em..