Get a timing advancer or whatever it's called, from Vito's, it's 25$ and seems to be really worth. Look at www.quadstore.com and "project banshee" That's real cool, they have the best dyno charts.
I would go for a K&N Filter (don't waste your money with Pro Flow, you can get the same exact result with just the K&N filter (email me if you want to know how). One thing that seems to be cool is the airbox lid from alba. Supposed to let as much air as no lid, but doesn't let water in. It think it sells 89$.
Shaving the head is a good idea if you can know how much to shave it.

 

Wow. Thanks for the site, Zorro. Anyone interested in upgrading a Banshee or Blaster should check it out.