As for hopups I would recommend the following:

• kHz inner and outer hinge pin plates
• Alum rear gearbox inserts
• kHz sevo saver (look at which version you have the 2.0 comes to a point and the 1.0 is more rounded)
• kHz quick change engine mount
• Alum front top plate
• kHz rear hub carriers or plastic modded to accept 8x16 bearings
• I personally like the inclined spindles and carriers, some don't
• Vented shock caps and bladder compensators
• v2 rear shock tower

The 2.3 front sway bar is nice too. I think that's it I like more bling so I added more but more is not necessary.