Is a car intake bad or good for your car?

I need experts to answer this. Can't find a straight answer online. I have a 2012 honda civic si and want to get a k and n cold air intake only if it is not bad for my car and gives me better gas mileage. Will it give me better mpg? My dad said not to get because the japanese engineers know the optimal amount of air my engine should be getting and believes it will entually ruin my valves. Any info is thanks.

Well, it shouldn't do anything bad to your vehicle for sure. The main purpose of air intake is to improve airflow and increase horsepower and torque on your vehicle. K&N intake kit replaces the factory intake system with much better functioning.