Warranty ?'s

I'm about to buy either a 2005-2006 Cobalt ss/sc. When I do buy it I want to put either the stage 1 or stage 2. I was just wondering if you do put those on is the car still covered under the warranty, since it come from gm? I know the kits for the SRT-4 still allows the warranty to be fine cause it comes from mopar, just wondering if that is the same. Also does anybody know the price for the kits?