I'm a proud new owner of a beautiful 08 white with black stripe GT500 and am ready to start playing. I've had a couple of mustangs built by a performance shop near me with incredible results and will be sending this car to them for the CAI,tune and pulley package in the next couple of weeks. My question centers around the exhaust package. These guys are steadfastly against me doing headers of any sort, in fact, they say it's not worth even adding an off-road x-pipe, just not enough power gain for money spent. Now, I'm not looking to empty my wallet, but I really thought these cars picked up decent numbers with headers and off-road x-pipes. I will undoubtedly bolt on the off-road x-pipe and magnaflow magnapack system for the sound, but I'm really on the fence about the headers. I would really like to hear from those of you have bit-off the header install and those of you who haven't bothered.