The effect of horsepower on gas mileage

[Matt Timion]

let's say we're not comparing apples and oranges.

For the sake of arguement, let's not compare a d15 with a b16, as they are entirely different. let's compare a d15b2 that is stock with a d15b2 that is modified to get more HP. Let's say both engines are MPFI and the only modification is the ITB on one engine.

It would take less work for the engine to get the same speed (when compared to the other engine). Wouldn't this equate to better gas mileage?

Or does this line of thinking only work for older non-computerized non-fuel injected engines?