So at what point...
 

At what stage of N/A builds will the fuel mileage go down?

From what I can guess, once you move to a larger injector or increase compression you're going to start loosing fuel efficiency, also if you hog out the head a lot. Any thoughts?

On the other hand, I/H/E, mild head porting, or a cam shouldn't effect it from what I can tell... but increasing compression is causing more resisitance to the rotation of the crank, and typically larger injectors don't atomize as well.

RE: So at what point...
 

To tell the truth on our engines loss in your milage will be slim depending on the tune.