Added headers, improved efficiency

[Telco]

1987 GMC S15 2WD auto ext cab truck

I just installed a set of Pace Setter headers on my 87 S15 2.8L auto truck. No other changes. Mileage increased from an average of 18MPG to 22.5MPG, and this is just off the first tank. I'm very consistent on how I fill my tank, been calculating the per-tank average for years. Won't call it a definite improvement until I've gotten 3-4 tanks through it.

All this was was a change in pipe diameter and where the exhaust comes together from the engine to the cat. I'm expecting it to slowly get better as the computer gets used to the new operating parameters, with any luck I might start seeing 24-25MPG out of it.

The engine also has a lot more power across the entire powerband with the most improvement on top of the RPM range, so it doesn't take as much gas to maintain a specific speed. Passing is also less of a chore.

Headers are made for almost every engine out there, and is a cheap way to boost both power and economy. With a fuel cost difference (based on 3.00/gallon) of 3.3 cents per mile, the headers will have paid for themselves once I've gone a little over 9900 miles. Total cost of the headers plus the install was about 325 bucks, all said and done.

Next, and final, exhaust change while it has a 2.8L is a quieter, better flowing muffler. I'm thinking either a Walker Quiet Flow or a 30 inch 2.5 in diameter glasspack, the rest of the system is 2.25 inch diameter. A long, slightly oversized glasspack should give me a nice, quiet tone without affecting velocity too much.

Calculations -
Cost per gallon divided by miles before equals M1
Cost per gallon divided by miles after equals M2.
M1 minus M2 equals cost difference per mile
Header cost divided by cost difference per mile equals number of miles that must be traveled to recoup cost.