Instant increase in horsepower! That's what you get when you replace your factory exhaust manifolds with performance headers. The science behind it is pretty simple - with factory manifolds on an 8-cylinder engine, you have 8 exhaust ports dumping into two manifolds at the engine block, forcing air through 2 pipes at the manifold. This creates a tremendous amount of back pressure. That back pressure decreases horsepower potential, fuel efficiency, and exhaust sound.
Headers route individual pipes to each exhaust port at the engine block. This decreases the back pressure at the engine and routes the exhaust into 2 collector tubes that creates easier airflow through the rest of the exhaust, however you decided to lay it out.
Just remember that the shortest distance is a straight line. Though you won't likely be able to have perfectly straight exhaust pipes, the less curves the better.
