"Side by side comparison of the SLP Loudmouth Catback (99-04 GT / Mach 1 / Bullitt) and a Stock Exhaust on a 2000 Ford Mustang GT. As you can hear from the sound clips above, the difference in both sound and style is world's apart. See for yourself. You can pick up the SLP Loudmouth Catback Exhaust for your 99-04 GT at AmericanMuscle.com. Check it out here: http://www.americanmuscle.com/slpexhaust.html 1999 2000 2001 2002 2003 2004 Mustang GT"