I have the 3 speed and a 15 tooth clutch bell and 52 spur, the stock spur was a 49. i want to keep the cost under 200 for sure. i haven't heard too much good about the k5.9 from hpi. the k4.6 i heard good things about and i can get that through hpi with the exchange for 160. the 5.9 is 180.