A lot of people
driving any kind of car/truck would kill for even a 10% improvement.
Most of us have Broncos with older plug wires and ignition components. Even the best of us will get at least a 10% improvement with this $140.00 outlay in parts and a half an afternoon's labor.
I have seen a lot of guys get 25%, 50% and 68% better mileage from this trick.
It's getting to the point where the parts required are almost the same price as a tank or two of gasoline.
No question a better Y-pipe and more efficient cat are number two in mileage increases and should be done as soon as the "Sixlitre tune up" has saved you enough gas to afford the Y-pipe.
It took me a year of improvements, but when I started I was getting 11 mpg and when I finished I had hit a record 21.6 mpg.
More importantly I could get 16-19 mpg during every day lead footed driving.
Don't delay do it or order the parts today !
Sixlitre