I just received an Email from Magnaflow telling me the exhaust for the GXP's will be ready mid november. They will email me when it is available. (p/n#16726) They have been the only company to respond to my requests for an exhaust system for my car.

The biggest difference in exhaust on any Grand Prix (performance wise) is from the downpipe. These guys have been making a better, higher flowing downpipe for the GXP for a couple of years now. Check the website out. They dont' have muffs or the remainder of the cat back, but really all you need is the downpipe, and pair of Flowmasters, and you are good as any kit.
The website is www.hoganperformance.com

Check out part # DP5S or DP7S depending on your needs. They are very good about answering any questions that you may have.

thanks,
I am going to order the DP7S. If you know anyone else who makes parts for the GXP let me know.

thanks for the info. I received the Hogan Performance down pipe with Magnaflow exhaust. I also recieved the Diablosport Predator programmer. the higher tuned program is great. seems loke a whole different car!!