Upgrading vehicle's exhaust system is a great way to build horsepower, free up trapped torque, and improve upon restrictive factory systems. The larger pipes, low-restriction mufflers, and tuned resonators of a well-designed performance exhaust system can make a world of difference on your vehicle. The net result is lower auto exhaust backpressure, more horsepower, more torque, and a much better sound. Replace for 04-06 Ford F-150 5.4 2006 Lincoln Mark LT 5.4 Fits 4WD Only - Driver Side NOT Legal for sale or Use in California, New York, Or Maine Emissions Models