What if we're a grumpy, younger individual?
A CAI might add a bit of horsepower (a few) as you approach redline. How often are you up there? You're not going to see any appreciable increase in MPG. Considering how much money and effort auto manufacturers are putting in to eke out a bit more MPG (auto start/stop, air dams, active grill shutters, etc.,) you can rest assured that if a few cents per vehicle improved MPG, they'd come that way from the factory.
Your truck has two valves per cylinder. That's your air flow restriction, and no CAI is going to fix that. But sometimes a placebo is worth its weight in gold...