You can get away without jetting it, but it runs SOOOO much better if you re-jet. Everyone that's ever run just a slip-on and later re-jetted kicks themselves in the butt for waiting.
The two kits that get the best reviews here and on any other Bandit board are
Holeshot (Stage 1 will run you $128 and includes a timing advancer) and
Ivan's Performance (his only 2G B12 kit is $130 and includes new needles - timing advancer not recommended with his setup).
Unfortunately, you just missed Ivan's Holiday sale. He was offering 15% off his kit, or 1/2 price if you bought it with a slip-on.
It'll cost you about the same to have either kit installed. I think Ivan's kit will produce more power than Holeshot's Stage 1, and is pretty close to Holeshot's Stage 2 Airbox kit.
Factory-Pro also offers a good product, but for some reason, it's not as popular as Holeshot or Ivan's.
Dynojet also offers a kit, but their Bandit kits don't get good reviews. They seem to be difficult to get dialed in. K&N offers (or offered?) a jet kit that is Dynojet's kit in K&N packaging.