04-06
Base: Single Exhaust, Single exhaust fascia, basic single cd sound system, usually cloth, generally hubcaps
GT: Dual Exhaust, HUD and 5 button dic options, Monsoon option, leather option, sunroof option
GTP: Supercharged, all options available
07-08
Base: Leather option, 5 button dic option, hubcaps or premium wheels, sunroof option
GT: Supercharged, all options available
Basically 07-08 had every option available on either model where as the Base models 04-06 were typically just rentals/ fleet vehicles.
My 06 base has actual rims and a 5 button dic but as stated has all the rest of the cheap crap
06 base open cone,2.5 inch dp into high-flow cat,window tint,drilled rotors.
97 GTP ubend delete,drilled and slotted rotors,de-badged,open cone,6k HID,All aftermarket speakers