From my experience its extremely difficult to validate MPG benefit marketing claims by any aftermarket product.
Exhaust wouldn't be my first choice as you have stated with most having increased noise. Cost per HP, or cost per MPG gain exhaust wouldn't the first thing I would go after.
Be weary of the K&N, while they flow relatively well they also allow a considerable amount of dirt to pass. This can be verified in the engine oil as sampled "silicon".
Wix from lab test usually test very well for flow and trapping for in the traditional paper filter form. If I were to go aftermarket intake I would seriously consider one of the from dry filters. There are two or three aftermarket companies that make OEM foam replacements. The dry foam air filter seem to be a solid benefit of flow with still having acceptable filtering capability.
I had a Fram, low expectations here, air filter on the Silverado that tested better than the abet old dirty AC Delco filter. I didn't expect the Fram to test well. Nor would Fram be my first brand of choice, but it did alright. The Fram doesn't provide any measurable flow difference over an OEM unit.
SCT has a considerable footprint in the Ford aftermarket programming and a good variety of SCT dealers. I've got a lower end SCT programmer, the 3015. Purchased originally through 5 Star with custom tunes. Tried to strike up a conversation with Mike at 5 Star about the shifting characteristics, he couldn't have been more disinterested. Then jumped to MPT for tunes. Really pleased with their patience, ability to listen, and attempting to deliver tunes that satisfy customer expectations. The out of the box SCT tunes are pretty good as well, slight power increase, better driveability, and 1 MPG benefit in mileage. Some people claim to see 2 MPG or more they claim.