if you yank the airbox, I don't now anyone who has done so that is still using the stock airbox. You would need to change the main jets. (costs about $5 each) I'd suggest using 110 Keihins to start and take plug readings to figure out if you need to go up or down from there.
that should keep you really busy.
if you buy a jet kit, be sure to get one made for no airbox.