Each Skunk2 Alpha Series Header features equal-length, sequentially paired, stepped primaries in a 4-2-1 tri-Y design that terminates with True Merged Collector with a 2.5-inch outlet. Skunk2's Alpha Header also include 02 bungs for OEM and aftermarket sensors. Each header is constructed from stainless steel with mandrel-bent tubing for strength, corrosion resistance and durability. The Skunk2 Alpha D-Series header also includes a donut gasket and a weld on exhaust flange, this included flange can be utilized as an option to weld the Alpha Header to an aftermarket exhaust. These features, paired with Skunk2's unique design specs, provide an extremely broad powerband that's applicable to a wide range of engine sizes and configurations.