For me, RPM arms and axle carriers were a necessity. Mine came with RPM arms (bought used), but I busted two axle carriers the first day out. I busted a couple RPM arms, but it would have surely decimated stock arms as well.
Ditch the dual steering servos for a stronger/faster single servo. Get rid of reverse and replace with a FOC.
Then, replace as you break, but not a lot breaks on the revo other than the engine bay getting tweaked and eating up spurs. In the end, that's why I got rid of mine.