Originally Posted by Arisenfury

Think of it this way, if you were to take a drink and drink it out of a straw until it filled up your mouth, then take the same drink and drink it without a straw by just tipping it in your mouth and it will fill your mouth much faster but it's still the same ammount of liquid. This same principle applies to an air intake. The intake valve is only going to let in as much air as it wants, with the stock airbox to get that air it needs it would be like sucking the drink through a straw, with a high flow intake it would be taking the same ammount of air it needs but by "gulping".

The only time the air in the intake chamber is really different is when you go forced induction which, as the name implies, forces the denser air into the chamber.