I have a Red 2004 Grand Prix GTP Comp G, the body is in great shape but want some upgrades. Have found the inferno hood, front facia and rear spoiler. Where can i find a Special Edition rear valance to fit it also?

Your best bet is to do a search for junk yards. You may be able to find one new at GM parts supplier, but experience has shown that they tend to be extremely expensive. Ebay is great too, just be sure that you get a reputable shipper.

Ok thanks ill just have to look around. Im goign to getthe inferno package too soon. Would it be difficult to take it back off for the winters ahead? just use it for the summer

Well, if you're getting the complete package (spoiler, air dam, and hood) I would say, if you have time and are good at body work yes you could change it. In my experience, the rear spoiler itself is time consuming because you have to re-tape the spoiler every time you put it back on and then get the tape off the car every time you take it off(at least with my Bonneville, may be different for GP). The air damn is dependent on the fasteners used. Every time you change a hood you have to be careful of alignment with the other panels of the car. So basically it'* left up to what you're capable of or how much you are willing to pay for someone else to do it. Another thing is that you may also stress the paint the more you attach and un-attach the pieces, but that usually depends on how careful you are. But that'* all just what I would think.

I would prolly just do the hood and the front air damn and leave the spoiler. I dont have much experience on body work but i can do it the right way or i will get someone to help me