The PLM H2B Swap / Prelude H22 4-2-1 Race Header. This two piece stainless steel race header for the H22 motor works on the Prelude Chassis and for those who are doing the h2b swap. Which is an H-Series motor on a b-series transmission swapped into a Civic. This 4-2-1 design takes advantage of the power of the h22 torque and gives you low mid and high end power. Perfect for street or strip. With equal length true step up header design, which terminates to a 2.5inch collector you get maximum power gains.