Mazda Miata MX5 94-97 1.8L Stainless Long Tube Header & Downpipe Race Manifold One Exhaust Header w/ built in downpipe with Gasket Features ONE O2 Sensor locations CNC machine flanges with TIG and MIG welded construction. T304 Stainless 1.75" primary tubes and 2.25" Outlet Although DIY is possible. PROFESSIONAL INSTALLATION is RECOMMENDED, NO instruction will be included except the manufacturer's original ones if there is any.