Dave, get a larger carb, the extra teeth drive sprocket, and a Bi-Turbo performance exhaust.
As for how much larger, ask around about size/jets/etc and see what combos have worked for other people...myself, I pulled the DelLorto and used an Encarwi(sp?) carb of a different design which seemed to work a whole lot better.
All of those are relatively simple to install (tho you'll do a bit of cussin trying to get the drive sprocket off to change it, I'm sure..) and do not require any change to the factory fuel/oil mix that I know of.
It's relatively inexpensive as well, and you will see a slight performance increase, mostly in top end, rather than accelleration, but it's probably your best bet for that kind of upgrade.
Ree