LRP or Nosram Brushless seem to be the hot ticket for the ESC..... and the motors are a thing of personnal taste...( with a few track size and conditions mixed in there ) I tend to prefer the Novak Light series since they are a little bit more "
USER FRIENDLY" on the bottom end with the same top speed.....
Here is a link to a good thread with some electronic layouts for the 501x
http://www.oople.com/forums/showthre...?t=1929&page=2