Ran the viper copperhead 4500kv combo for the first time this weekend in my losi scte.This weekend was the king of the hillbillies race at tcrc,I was able to tq and win the main.The viper system worked flawless I'm very impressed for the low cost of these systems.Does anyone use the 3900kv in 2wd sct.like to put viper in my 2wd also but want to keep it cheap and simple.