As said already it's a great car out of the box. RB6 rear arms and the thick roll bar kit are worth considering, pistons wise a lot of guys have found better results with 3 hole rather than 2 hole. Gear diffs are expensive but a nice to have, especially if you don't like rebuilding ball diffs. Worth looking on the facebook page for more info:
https://www.facebook.com/groups/492050687601155/