SLP Loud Mouth Cat-Back Exhaust System for 1999, 2000, 2001, 2002, 2003 and 2004 GT Mustangs and 2003-2004 Mach 1 Mustangs. Are you looking to have the loudest Mustang on your block? If so you might be interested in purchasing this Loud Mouth Cat-Back Exhaust System from SLP Performance Parts. This SLP Loud Mouth Cat-Back Exhaust System is a direct replacement for all 1999, 2000, 2001, 2002, 2003 and 2004 GT Mustangs and all 2003-2004 Mach 1 Mustangs. This SLP Exhaust System is constructed out of high-quality 2-1/2″ stainless steel tubing that is mandrel-bent. The mandrel-bent exhaust provides better exhaust flow which leads to better performance. SLP installs bullet style mufflers that provides a deep aggressive exhaust note that will really stand out in a crowd. The Exhaust exits out the rear bumper of your Mustang that include two 3-1/2” Exhaust tips that feature a mirror-like finish. SLP Performance is one of the more experienced names in performance modifications, with over 25 years of experience working with muscle cars. Based in Michigan, SLP Performance stands for “Street Legal Performance,” and they guarantee that every one of their products will have the best engineering practices and high quality that far exceeds the standards set by the rest of the industry.