Read about Brake Specific Fuel Consumption and forget everything you ever heard about MPG. Unless you have corroborating proof, don't believe much of what you see with your own eyes. MPG threads bring out some of the worst in the Internet.

 

So true. When I had my 460 I didn't call it economy, I called it consumption.

 

I can squeak out 14 mpg when empty and driving it like granny, usually 12-13, 9.5-11 at 11K with the TC.

 

There are a ton of little things that will add up. Synthetic wheel bearing grease in all 4 corners, synthetic in the rear axle. Do not expect to get any kind of mileage if you have to have an automatic, I guess that's the first thing. I run a Banks stainless complete exhaust system, make sure your O2 sensor doesn't have over 75,000 miles or so. They get slowly coated and become "lazy" With a break out box and a VOM you can count the number of rich/lean switches in a second. Lazy ones are down around 5 or 6, a good one will be around a dozen. Synthetic in the engine, trans and transfer case. If you're over 100,000 miles you will benefit from a new timing chain/gears. As they wear they retard the cam. Keep plugs fresh, 20,000 miles max. Electric fan for the radiator and so it goes. All these putzy things add up. I can pull 16,000 pounds on my goose trailer and get 14-15. this engine loves that 22-2400 rpm range when pulling, which is around 70 with 4:11 gears. Lugging with a load, will actually destroy your mileage. I'm in the process on installing a Gear Venders overdrive on my 97, which will give me 10 speeds and one on top of 5th when running empty. Lots of attention to detail will pay off. You're just enhancing the factory unit, for the way you drive your truck. ECCIV systems are fairly simple and if you understand what ea piece is doing You can fiddle away forever. There is NO magic bullet, just enhancing what you have. Make sure your alignment is right on................

 

this,

i once drank the cool-aid about intakes and exhausts - luckily i survived