I installed 509 No Timing onto one of my old Justock. The process was a bit clunky, for starters didn't find 509 anywhere. Tried to upgrade my Hobbywing Link and it said it was up to date,even though a newer version is on their website. Had to just download the newer Link s/w manually, and install it manually. Then 509 was available. Flashed the Justock fine.

Use 100% brake force and setup Anti Lock Brakes in your transmitter. The car will brake better and is easier on the spur gear since it gets pulsed instead of locked up.