I run the original 501X, I have had it for 3 years and do not use any updated parts as my buggy is fast, nimble, strong and fun to race (club racing). I only changed the front diff pulley from 35T (overdrive) to 36T, that tip came from Hupo nearly three years ago at the IIC Onroad Championships here in Las Vegas.
My hopups:
I have alloy steering, tech racing servo stays and sway bars (not used)
