Not that I wanna hurt any feelings, hell if you feel like a performance MAF sensor gave you a little kick, then cool. Like it was said, it wasn't an increase in air flow that gave it the kick, it was the manipulation of the air fuel ratio. A tune would've been a better way to go. It probably leaned it out; I know my stockish N/A 4.6 stang responded hp wise when leaned out. The factory can only go so lean because you run into excessive NOx (which is one of those "evil" emission gasses) if gone too far. You have to be careful when you change the tubing diameter that the MAF sensor sits in. Anything bigger or smaller with no tune will/can affect the air fuel ratio (bigger tube=lean/smaller tube=rich) (even if the stock MAF sensor is used). Any tube that changes more then a few mm's needs a tune imo. A MAF sensor is only taking a SAMPLE of the air thats being drawin through. The MAF sensor can "feel" velocity but has no idea of the volume of air, thats for the PCM to take and calulate then apply to the fuel curve/map. If you add to the diameter of the MAF tube, the volocity of the intake air charge decreases, giving the MAF sensor the false reading that the engine is pumping less air, so fuel trim is leaned out to compensate.