For Scion xA/xB 4-1 Design Stainless Steel Exhaust Header Kit - 1NZ-FE Engine Made of high quality steel with 4-1 direct bolt-on design TIG welded CNC machine flange Metal gasket included / Inlet: 1.25" / Outlet: 1.75" 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)