I have a 90 tooth spur at the moment, bought a whole bunch of different spurs and pinions to fool around with. With the 18/86 combo my motor was only getting up to 130 and the esc was barely warm. Batteries didn't even have a slight difference in temp though...which is a good thing...lol. I just have this truck to bash around with but nothing too extreme. We have a big grass field behind our complex, that is where we mostly play with our trucks. I am pretty happy with how the truck is running, it is fast but not crazy uncontrollable fast. I just bought a 3s pack from HobbyKing and it seems a bit too much for this truck, always seems to be puttin it on its lid so I will have to mess around with the gearing more. I just picked up a rustler since it was cheap so that will be another project that I will be working on, might try and go with the velineon combo for this one.....well have to see what comes into play. Thanks for the info though, always good to hear what everyone suggests.