DNA Motoring HDSHP97NS41 Stainless Steel Exhaust Header Manifold Made of High Quality T-304 Stainless Steel with Computerized Mandrel-Bends for Strength and Durability i.e. Maximizing Smoothest High Exhaust Air Flow Rate 4-1 High Performance Racing Spec. Design, Produces the Most Top End Power Offers the Best Flow Characteristics for the Engine at High Engine Speeds Increase High Flow Air, Instantly Gain 10 -15 Hp. / Tq. Inlet/Outlet: 1.875" x 1.5"(Oval)/2" / 10mm Thick Header Flange