My Viper system quit working in my B44 today so I put in a Castle Sidewinder ESC and a Castle 3800KV 4 pole to see how it would do. I like it better than the Viper 10R with Viper 6.5 motor. This thing is crazy quick now. There are to triple jumps on my backyard track that I couldn't clear with the Viper gear because of short run ups but I'm getting them now with the Castle combo. I think I'm going to get the Viper stuff fixed and sell it and keep the Castle combo in my B44. I think it's either the sensor wire or sensor board thats bad because the ESC wont sink with the motor now? Oh yeah the Castle stuff is staying a lot cooler also. The Viper ESC and motor would get pretty warm even in 50 degree temps.