The trx .15 pro is a really old engine, its design is over 10 years old. I had one on my original t-maxx. It is a gutless engine that is extremely hard to tune. In fact it at one point caused me to get sick of rc's and put them on the shelf for several years. I literally spent over a month trying to tune it only to have to retune it everytime i wanted to use it. It was never happy with any tune i put on it but tolerated the settings once in awhile. The best thing i ever did was drop in an os motor in its place. Once i did that my rig had tons of power and was easy to tune and maintain. So i concur, take that motor and throw it as far as humanly possible, its a steaming pile of garbage.