Hello!
That probably means with absolutely nothing connected to the compressor. Once you put something there, that is partially blocking the output - like the airbrush, or a pressure regulator - the airflow drops. How much does it drop, is another question. So the message to you is in effect: No matter what you do, you won't get more than 1.4 CFM out of this baby here. Hope it helps, have a nice day
Paweł