with brushless make sure to upgrade to ball bearings, aluminum shaft and aluminum motor mount. i would lean towards a sensored system over a sensorless system in a tt01 because the sensorless systems arent as smooth so they jar the gears a little more. Also anything faster than a 8.5t (5000kv) and the car will sound disgustingly (or awesomely) loud but the car will hold up to it fine. i ran a novak 7.5T in mine for a long time and then a 6.5 slyder for a while.