A good 12v hopper, nitrogen if you can afford it (a 68/3000 steel should be sufficient), and get a squeegee or two. A pack would be nice as well, like say 4 or 5 down from Extreme Rage, Redz, Indian Creek, or Mpack.
yeah i agree with those idea too! either a 12v revvy or a ricochet. nitro isnt a bad idea but if i were u i would get a larger tank than a 68/3000, unless u will always have access to a fill. if u have the money PMI Pure Engery nitro tanks are great!(check out at http://www.actionvillage.com/paintball-gas-systems-nitrogen-systems-pmi-nitrogen-systems.html) i suggest a redz pack as well, but i have heard good things about Rase packs and Extreme Rage paqs as well.
Someone using a Piranha isn't likely to need more than 68/3000 under the majority of circumstances. As for Pure Energy, I use one successfully and would recommend it and Crossfire with equally good standing. Nitroduck has been a consistent performer as well, though I don't currently own one of their tanks. I did, however, for 2 years before and it did perform for me admirably.