Remember guys... he said the SPORTS not the standard 7.5 or Kanai...
My list of upgrades:
Until I replaced all of this I was breaking parts every bash as Team said.
Front CVDs (missing pin on one dogbone and 2 broken outer drive cups)
13t STEEL Spur gear instead of stock 15t plastic (gs21 engine does not have enough low end for 15t)
Front and Rear Alum Chassis Braces (stock does not come with fron brace)
Rear Alum chassis brace mount (where it connectes to the wing support)
Team Bluestar Front/Rear alum shock towers (bent 1 rear and 2 front on bad landings)
K2 Front Shocks (3.5 mm) --stock front/rear are only 2.5 i beleive--
Ofna 9.5 threaded Rear Shocks (3.5mm) --bent 5 shock shafts, none since upgrade--
Titanium hingpins all around (stock steel were bent causing suspensions to bind)
Titanium adjustable front turnbuckles (stock are not adjustable)
New Tires (RTR tires do not come with Foam inserts)
3 Shoe teflon Clutch rather than 2 shoe alum (later upgraded to fironi sliding clutch)
Last but not least will be the engine, header, pipe, engine mounts, and spacers. The GX21 I have in there now allows for great fun but just is not competitive.