I sincerely mean no offense with this post and I don't mean to come across as a know-it-all (I don't know much at all) but I can't buy the 2-3 mpg improvement with a new cold air intake.
For heck's sake, if that can be accomplished for a few hundred dollars, Ford would find a way to do it for a fraction of the cost and introduce it across the line. Improving MPG across an entire model line would be an incredible feat for the company and its CAFE numbers. They would be all over that.
The engine only uses what it needs, it doesn't need all the air that the OE intake system is capable of delivering while cruising at highway speeds. We're not talking wide-open-throttle. There is something else going on with the numbers here.
Think about it like this, if the engine is putting more air through it because the new setup is capable of supplying it, it's mixing more fuel with that air. What do you think that would do to the MPG numbers? I'd suggest you put a few tanks through it hand calculating the numbers. The gauge on the dash can be a real liar at times.
Okay, I'll step down from my soapbox now.