gas mileage worse after chrome intakes., i thought it was supposed to get better? Options

[Tech9ine]

hey,
I installed this chrome intakes ram air on my ST a few months ago and since I've installed it I've gotten about 100km/tank less than i used to with my stock intake. Was I wrong in thinking the gas mileage would get better if not stay the same? could i have possibly done something wrong? (it's pretty simple, i don't think i goofed on anything.)

[Hanyo]

Cold air = more power. More power = less revs needed to get the car moving.

if your logic was good, every car would get extremely good mileage in winter. But its quite the very opposite, it drops buy almost 25% +

My mpg decreases in the winter also. I warm up the car longer, and use more accerioes such as heater, windsheild wiper and rear defroster. All this electricity use puts a heavy strain on the alternator and this reduces power and fuel effiency.