Maximizing Smoothest High Exhaust Air Flow Rate. 2 X 4-1 High Performance Racing Spec.Computerized Mandrel-Bended to Maximize Air Flow Smoothness. TIG Welded CNC Machined Flange for Resistance against Cracking and Wearing. Increase Engine Exhaust Output and Efficiency. Standard SBC 3-Bolt Flange Inlet / Outlet: 2.875. Increase High Flow Air, Instantly Gain 10 -15 Hp. Professional Installation is Highly Recommended (No Instruction Included). 1 X Set of Header Exhaust System. Hardware as Shown in the Picture Above. Thank You For The Opportunity To Serve You! The item "For Chevy/Pontiac/Buick SBC 265-400 Small Block Stainless Steel Exhaust Header" is in sale since Friday, May 15, 2020. This item is in the category "eBay Motors\Parts & Accessories\Car & Truck Parts\Exhaust\Exhaust Manifolds & Headers". The seller is "performotor" and is located in Texas, TX. This item can be shipped worldwide.