The factory air intake is designed for low engine noise. Well, that is okay, but it compromises air intake, and subsequently, performance. Factory air intakes or rather OEM air intakes are designed to draw air from beneath the hood, and the air they draw is normally hot.
Unlike cold air, hot air doesn’t have much density, and as such, there isn’t as much oxygen in hot air as you would find in cooler air. Keeping in mind that oxygen is what is needed for efficient combustion to happen, replacing the factory air intake with an aftermarket cold air intake is a great move. It improves performance, sound, and fuel efficiency.