DNA MOTORING HDS-HC88 Stainless Steel 4-2-1 Exhaust Header for Honda D-Series Tig welded CNC machine flange O2 sensor bung insertion/metal gasket included Increase high flow air, instantly gain 10 to 15 hp./Tq Inlet: 1.75"/outlet: 2" Color: Polished Chrome Materials: T-304 Full Stainless Steel Surface Finish: Chrome Polished Stainless Steel Inlet/ Outlet: 1.75&#034; / 2&#034; 88-00 Honda Civic D-series Engine SOHC 88-91 Honda CR-X D-series Engine SOHC 93-97 Honda Del Sol D-series Engine SOHC Direct Bolt-On Installation, Requires No Modification. Professional Installation is Highly Recommended (No Instruction Included). Headers are one of the easiest bolt-on accessories you can use to improve an engine&#039;s performance. The goal of headers is to make it easier for the engine to push exhaust gases out of the cylinders. When you look at the four-stroke cycle in How Car Engines Work, you can see that the engine produces all of its power during the power stroke. The gasoline in the cylinder burns and expands during this stroke, generating power. The other three strokes are necessary evils required to make the power stroke possible. If these three strokes consume power, they are a drain on the engine. Our professional technicians do heavy research and development in testing car applications and fitments for our products. We also do rigorous testing on the strength, durability, as well as longevity of the material in order to make sure when the product arrives at the consumers end that its ready to go without worries.