DNA Motoring HDCFM96LT Stainless Steel Exhaust Header Manifold [For 96-04 Ford Mustang GT] Made of high quality steel covered with metallic ceramic coating.with 2-pieces 4-1 direct bolt-on design TIG welded CNC machine flange O2 sensor bung included / Inlet: 1.75" / Outlet: 2.25" 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)