SuperMAXX Stainless Long Tube Headers are an excellent way to bolt on 25 hp and 15 Ft. Lbs. of Tq. to your 2014-2017 GMC / Chevy 1500 Series Truck.. Although a tune is recommended, these power gains were before the tune! A power tune could add another 20-25 hp. 100% Stainless Steel construction with a Limited Lifetime Warranty makes the SuperMAXX header second to none. 1.750” primary tubes and a 2.50” collector make a great combination for stock engines and/or upgraded power plants. Fits with automatic or manual transmissions and takes about 4-6 hours to install. Comes complete with a detailed, full color instruction manual for easy installation. O2 Extension cables, triple layer stainless steel gaskets, header bolts and all installation hardware are included. Designed for use with Dynatech Y-Pipe..Comes with or without catalytic converters