Just run it and enjoy and replace/upgrade as necessary. Keep an eye out for a deal on some RC8B Big Bore shocks and the alu top-plate.
Eventually - as with all RTR's - [/PHP]some better, faster, stronger servos would be a huge plus.. For ex. 2x Savox 1258's..
IMO a 17T CB will give you more speed without sacrificing anything down low.. Unless you just really want to drift all the time..
A 2035 pipe is cheap and a worthwhile upgrade at some point.
The only real potential breakage point with the SC8 and RC8 is the upper front arms, especially the right it seems in my case. If you take a hard hit it might give.. So as far as spares to have on hand, I would have front upper arms for starters.
Again though, it's a tough truck, and you can run it stock for starters and just have fun and see what happens and after you've run it a bit see what you think.. No real absolute musts right away..
Ran mine the other day indoor:
http://www.youtube.com/watch?v=4LBUR8XVsZU
http://www.youtube.com/watch?v=E3306iVGwr0