Did you know that putting headers on your car will actually do more than make it look cool?Headers are meant to reduce the back pressure from the manifold caused by having only one common manifold that all of the cylinders have to share. Each cylinder gets its own exhaust pipe, which is cut and shaped so it is the same length for each.
The pipes come together into a larger pipe, or collector, where as all of the exhaust pipes are the same length, they reach the collector at the same time, so all of the exhaust is pushed at the same time.
This reduces the back pressure and therefore makes it easier for your engine to complete the 3 strokes in preparation for the power stroke.
