This system produced gains of up to +20 HP and +23 lbs. x Ft. TQ., as measured on our in-house dyno.This system is constructed of 1-5/8 IN mandrel-bent 304 stainless steel tubing for maximum strength and durability. This coating combination reduces the outside surface temperature of headers and reduces engine compartment temperatures. Factory style laser cut machined mild steel flanges are used used for a secure leak-free seal. These headers retain your stock catalytic converters and are a direct bolt-on installation which requires no cutting or drilling to provide a hassle-free installation. Mitered collectors decrease turbulence and increase exhaust velocity. The result is increased horsepower, torque and improved throttle response. A Machined ball flange ensures a leak-free seal over the life of the vehicle. 100% MIG-Welded for race-proven strength and durability Twisted Steel 1-5/8 IN to 2-1/2 IN 304 Stainless Headers w/ Titanium Coat Finish Ford F-150 15-24 V8-5.0L Ford F-150 15-24 V8-5.0L