Jordo!

As a general rule, more air ingested requires more fuel; thus, more power typically means worse gas mileage.

But here, we're talking about maybe 1 MPG worse at most. Possibly no significant change depending on how you drive.

The only way to get "free" power, is to reduce parasitic losses (e.g., lighter mass on rotating drivetrain components).

Another exception would be to run leaner under load (i.e., use less fuel), which, might result in more power, if the tune was running overly rich and quenching timed spark events (this car runs pretty rich up top from the factory).

Neither should result in any appreciable losses down low, both should gain mid and up top. A tune can mitigate all of this, of course.

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