These Hooker LS cast iron exhaust manifolds have been designed to hug close to the engine block so they fit into a wide variety of replacement engine swap applications. Their contoured design aims the exhaust directly at the exit port for greatly improved flow. They are cast from high silicon moly ductile iron to provide durability, leak free performance and less under the hood noise than conventional headers. The Hooker LS cast iron exhaust manifolds are recommended for strong performance on engines up to 500 horsepower and are available in plain as cast finish. They also feature 304 stainless steel mating flanges to help provide a leak-free installation, and a two bolt exit flange which can be used with OEM style gaskets and fasteners for an excellent seal.