I was thinking about upgrading my wheels a while back, and I (think) learned a few things.
Two or three inches is a lot, even though your looking for lightweight wheels, you'll still going to feel a bit slower. Since there is a whole lot more distance for those wheels to roll, it's going to take longer to get started. Plus, you'll need a much lower profile tire, and if you drive them on the streets, and you hit a curb or something, wave bye-bye to the wheels. If you plan on racing it, I would suggest getting a different set of wheels, and put performance tires on those, either autocrossing, drag, or whatever tires you want.