Dog bones.... Make sure you change to "Thousand Direction" because the original dog bones are very easy to fall off.
If you change motor to a faster motor, make sure you add heat sink.
If you jumps a lot, add oil shocks and slipper clutch.
Mine has already added:
"Thousand Direction" dog bone by 3 racing (Do not use Tamiya's for DF02 as they do not fit and Tamiya has not make one for DF03 yet)
Tamiya oil shocks
Tamiya slipper clutch
Tamiya one way bearing
Tamiya lightweight steering rod
Tamiya lightweight drive shalf cups
Tamiya axle "6 corner"
Good luck.. it's a fun little buggy.... I have 2 myself....