Our Spec 3 Tubular Manifold and Up-Pipe for the Subaru Impreza replaces the restrictive standard cast iron manifold and improves exhaust gas flow thanks to its stainless steel, CAD-designed construction. You will also benefit improved throttle response and increased power output. Features: Constructed from T304 stainless steel Unequal length header pipes 3 bolt Up-Pipe flange Improved throttle response and gas flow Gaskets included Please note: due to 3 bolt Up-Pipe flange this manifold can't be used with the standard Up-Pipe and must be used in conjunction with the supplied Up-Pipe.