Does cold air intake really make a difference?

A "cold air intake" does not actually induce cold air into the engine, but rather air that is not "hot." "Hot" air in the intake would be the result of an air induction system that allows air from right around the engine block or radiator to enter. The "cold" air would be any air that is not pulled from directly around the engine block or radiator, e.g. induction from the fender of the vehicle. You never really want to pull hot air in, but the difference between a stock air intake and a cold air intake is marginal, but depends also on the vehicle. A cold air intake will generally increase performance only marginally. But every bit helps if performance is what you are going for - if your car or truck is built up and made for performance, then the benefits will be greater on a high performance Corvette ZR1 motor as opposed to a 1984 4-cylinder Toyota Camry. Hope this helps!