How long have you had your SHO, Skibbidy? Can't be many miles on it, since it's a '14. So the SHO's still breaking in, probably too early to tell any mpg differences. Performance difference, that's a rather complicated story. The filter may flow better, but the stock system flows pretty well already. Exhaust upgrades are needed to take advantage of the air filter/intake upgrade, and show perceptible gains seat-of-pants or on a dyno. K&N's numbers are "generalized", I'd be surprised if they have SHO-specific numbers.