I have a used Borla Cat-back Exhaust System (Borla Part #14834) that will fit a 1999-2004 Mustang GT. I bought the car with this system on it and just upgraded to a system that better fit what I was looking for. This system was only on the car for roughly 3 years (less than 20,000 miles) and hasn't seen any winter driving, very rarely rain. Stainless steel so no rust or corrosion on it. All the hardware that came with it is included, and it will fit to any stock system from the mid pipe. All of the hangers mount to the stock and it bolts directly to the stock mid pipe. This is a really easy install for anyone that knows how to turn a wrench. Asking $400, but it's definitely negotiable. This system retails at over $750, so you can get all the benefits of the new system with some minor use at a greatly reduced cost. Let me know if you want to see any pictures or want to come take a look.