VFC's are more or less field-ready out of the box. You won't really know what kind of upgrades should be done until after you play a few games with it. Also, the kind of upgrades that you want to put in completely depend on your play style. If you want to just reach out and touch people from a distance, then focus on putting a good hop-up unit, bucking, tightbore barrel, and getting consistent compression. If you want to play close engagements more, then choose faster motors, high-speed gears, etc.