wouldn't your loss in MPGs be more related to the higher air flow? it was my understanding that the more air that passes over a MAF sensor, the more fuel it dumps to accommodate the new air:fuel ratio, thus the increase in power and loss in MPGs.
Simply put, not really.
Airflow is regulated by the Throttle Body. Based on MAF sensor output, the ECU will adjust timing of the fuel injectors to match the stochiometric mix, which is also based on a ton of other sensors.
If you are making more power at the same throttle position, then you are taking in more air, and the ECU is delivering more fuel, so in part, yes, you are right.
However, if you
drive the same, the idea is that you go by seat of the pants and not gas pedal location. If it feels the same and the pedal is not pressed quite as far, then you're running a slightly higher airflow and fuel count than what you did before, but your RPMs are lower, therefore consuming less fuel for the given amount of power you need and the duration that the throttle is pressed.
Make sense? Since the engine can make the same power at a lower RPM (on acceleration, not at steady speeds), there are less combustion chamber detonations per minute, and that offsets the slight amount of extra fuel per combustion that you are using compared to the stock configuration. On the highway at steady speeds, the RPM's are set. The higher airflow number helps here because to maintain the speed, you only depress the pedel enough to keep you going. If you're making more power at a given RPM, you essentially back off the pedal to the new "balance point" to maintain your speed. Doing so closed the butterfly plate in the TB ever so slightly, also reducing the CFM of air through the intake ever so slightly. The MAF senses this and makes a fuel correction accordingly, thereby using less fuel.
Works in theory. Didn't work in real life for this application.
In other words, the intake tube is not the "bottleneck" to fuel efficiency.
