When I started building my truck last year I was surprised by the mileage increase every performance product stated it accomplished:

injector nozzles -- 1 to 3 MPG increase
tuner box -- 1 to 4 MPG increase
Air Box -- ?
Larger exhaust -- ?
Aftermarket turbo -- ?
Water/meth injection -- ?
Programmer -- 1 to 4 MPG increase
Torque converter
Co-pilot
Fuel additive

Every one of these items claims better mileage.

I do have much more power and love it, but I do not see a bit of mileage increase. Yet, I don't see a decrease either. Good enough for me.

I have a problem keeping my foot out of the boosted performance, though. Perhaps when that dies down I will accurately measure MPG.

 

If they all played together like they claim they could, you would get around 40 mpg. Since that's not going to happen, find a small, scrap piece of 2X4 and wire it to the bottom of your accelerator peddle. That will increase your mileage and it's virtually free.

 

Way too funny!

 

But true!