Exhaust Header for 2008-2017 Subaru Impreza WRX/STI EJ25 SPELAB SPELAB Turbo Exhaust Manifold for the Subaru WRX and STi is an OEM replacement (using the standard 2 bolt uppipe connection) which comes with gaskets and a heat shield blanket. The SPELAB headers are lighter and flow more efficiently than the factory manifold which will increase your horsepower and torque while giving you a more aggressive sound. Fitment: 2008-2017 Subaru Impreza WRX/STI EJ25 Specifications: Brand Name: SPELABCertificate: ISO9001:2000Application: Automobile Exhaust HeaderMaterial: Stainless SteelSurface: Mirror PolishModel:EH28965 Exhaust Header VS Manifold, which is the better choice? The structural differences between exhaust headers and manifolds are the material and size. From the material, exhaust headers are made of lighter, thinner steel, while exhaust manifolds are made of thick iron. Exhaust headers are also longer than exhaust manifolds. When in use, exhaust manifolds create back pressure, which lowers performance. Because each cylinder of the engine is given its own tube, however, headers eliminate this problem; thus, allowing the gases to exit without the creation of back pressure. Therefore, exhaust headers are a BETTER choice than an exhaust manifold.