DNA Motoring HDS-BBC-Hugger Stainless Steel Exhaust Header Manifold Made of high quality Steel with 2-pieces 4-1 direct bolt-on design TIG welded CNC machine flange Metal gasket included/ inlet: 1.75"/ outlet: 2.5" 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)