Designed to allow you to customize the sound of your F-Body. By changing the block off plates you can adjust the SPL (Sound Pressure Level) to your taste. For use in Cat-Backâ„¢ systems 14780 14464 14555 14888 and 14813. Premium T-304 stainless steel will never rust. Precision computer numerical control (CNC) manufacturing ensures an accurate fit. Million-Mille Warranty.