Your factory exhaust manifold also known as "headers" is designed only in part for efficiency and power. As a result, maximum exhaust flow (power) is not achieved using factory headers, regardless of other performance exhaust modifications. To maximize flow and power, a better design is required.

Maximize Flow to Maximize Power

Mifune Racing headers increase flow and power by using larger diameter tubing and an equal length design, meaning all pipes leading to the collectors are the same length. This design means that as each cylinder fires, the exhaust gas pulse released arrives at the collector following the previous pulse in perfect synchronization, creating a perfect, uninterrupted exhaust gas flow. This smooth flow means MORE flow and more power.