I've got one on my GT, and am very happy with it. It's a noticeable bit louder than the stock one, and a good deal lower in tone. Has a nice rumble when crusing, and a pleasingly loudness when when you accelerate. It's made by the OEM supplier, so perfect fit and made of stainless steel, as well as no drone.
Sound type/volume is somewhere between stock and Flowmasters. Overall, a nice catback for someone who wants a classic musclecar sound, but doesn't want to scare pets and little children when motoring down the street.