I have 1998 Camaro SS that I wanna sell and buy a 2007/8 GXP. All the questions are for a GXP. Wanna know how happy are you with yours?? Who's the aftermarket?? Would like more info on the drive train e.g. engine bolt-ons, best exhaust, suspension upgrades, etc. Did all GXPs come with tap shift?? How do I know a true GXP from a non GXP besides the fenders?? Is there a write up for info on the GXPs?? Please throw in anything else that is good to know. Thanks.