Unless you take a "whole system" approach to intake, exhaust, and carburetor changes, you're not likely to see much, if any improvement in performance or gas mileage. Try adding one big link to the middle of a chain, and see how much the strength is improved. Running a matched-capacity system, air cleaner to exhaust tips, with a definite goal in mind is the only way to get any significant gain in either power or fuel economy, and getting more power and gas mileage at the same time is a pipe dream. You build for one or the other, and accept whatever the other end of the spectrum provides. I would not consider headers for anything other than a full-competition engine- - - -they're just too much hassle. One possible exception might be cast iron split manifolds, but I would NEVER use a steel-tube header on a street engine. They're too noisy, and I don't like dealing with leaks or changing flange gaskets every few weeks.
Jerry
Last edited by Hotrod Lincoln; 12/18/2009 4:10 PM.
