I have a 2006 5.4L FX4 SuperCrew w/ 6" lift and 35" tires. Just installed the Edge but I'm looking to add either of the following to further improve power and MPG - currently getting approx 10-12 in city and would like to at least get back to 14 mpg stated on sticker. Please advise which of the following mods will provide the best bang for the buck.

New Intake (AEM Brute Force) and Exhaust system (Magnaflow)

or

New 4.56 gears (currently have stock 3.73).

 

The intake might help a tiny bit but the bigger (number) gears will go the other way, won't they? The bigger gears will help handle a heavier truck, towing, lots weight in back, etc. but I think they will rob your city mpg.

I get about 15 mpg day-in-and-day-out which is 50:50 city and highway (55mph) driving. Goes up to 18 for long highway trips. I would expect to get about 12-13 drivng city all the time.

 

Not sure about mpg...Just got off the phone with local 4WheelParts service rep...He claims going to the 4.56 gears on my truck should get me 2-3 mpg more than my current configuration. Will also add more low-end torque and high end speed. He basically said this mod will make up for the lost mpg due to running bigger tires/rims with 3.73 gears.

Seems to make sense, but I'm wondering if it's just a sales pitch. Besides the job is going to run approx 1500 so not sure if it's worth it.

 

I don't know about 2-3 MPG, but you will pick up some. The shorter gears will help you off the line around town. They won't ADD any power, just put you back in the correct powerband. Everything you said will help out some. Some more than others. The Edge is going to give you biggest jump. The intake and exhaust will give another 2 MPG maybe on a good day.

 

those gears will cost you a lot of mpg.. not gain.