I purchased 3of these, one went into my stampede 4x4. Another into my LCG slash 4x4 and the 3rd into my crawler. The speed is ok but seems much slower than a stock slash servo. Once the fast vehicle is rolling at a decent clip then the servo picks up a little more speed. It's just fine for crawling as speed isn't needed. A really great value and I will be getting more of them.