To be completely honest, the kit (stock) set up is awesome! You dont really NEED to do anything special. But if you want to make upgrades to it, first things first, buy different ball cups. RPM and Jconcepts are the best in my opinion, the AE low friction ones are great too. IF you wanna run stock motor, I would suggest an aluminum top shaft at the very least. It lightens the rotating mass and gives it much more punch and helps keep motor temps down. You can always get the MIP puck system if you want to spend the money on it, makes a big difference as well. Another thing I liked a lot was the Jconcepts carbon fiber front tower, kept snapping the stock one and had no issues after I bought the JC one. The AVID shock stand-offs are a MUST as well, you will fly through the standard aluminum AE ones if not. Lastly, I would recommend but certainly not a must, is the AVID centering kit. I loved that kit.

Pretty much, It's all up to you and your budget. If you have the time, the budget and the will, then by all means, get all those things. but if not, you will still enjoy the B4.2 right out of the box!