For Ford Mustang 2x4-1 Design Stainless Steel Exhaust Header Kit (Polished Chrome) 5.0L V8 Made of high quality steel with 2-pieces 4-1 direct bolt-on design TIG welded CNC machine flange Inlet/Outlet 1.25"/2.25" / Metal gasket included Increase high flow air, instantly gain 10 to 15 Hp. / Tq Application: Please check part finder on top of the page (Professional Installer is Highly Recommended) (No Instruction Included)