As said, ceramic (3/32") diff balls, & i use these diff rings:
http://www.apexmodels.com/gbu0-prodshow/XR305082.html
Uprated nylon idler gears (i use Pt No. AR28T)
I somehow broke 2 front axles in 2 races (Ansmann Pt No. 125000441/Team C Pt No. T02042)
Front chassis plate (125000407/T02008) can break.
I've broken a couple of rear hub carriers too (125000412/T02013)
It's much easier to (& cheaper) to not crash/get crashed into & you will be fine
