I ran a set of home built custom headers on a 440 Dodge pull truck. We ran equal-length primary tubes that held one cylinder's volume each, into a 6" diameter collector. The primary tubes were 8 feet long, 1 3/4" in diameter, and exited under the cab where the inner fenders used to be. The tubes from cylinders 3,5,and 7 extended into the collector so each one was the same length as #1. We had massive low end torque with that setup. Unless the tubes are all the same length, there's no reason to run headers.
Jerry
