Thanks WRX! I'll order the jet kit and then do it then. If I put on an exhaust later will I need to re-jet it?Don't do it unless you are doing the jet kit at the same time. The bikes run lean from the factory to pass emissions requirements, and that is with the little airbox opening. By enlarging the opening, the bike will run even leaner. Running lean means running hot, and could cause damage.
Do it at the same time that you do the jetting, it only takes 5 mins.