I don't think its that hard to believe at all. If you ever actually look at a stock intake, there is practically no airflow at all. A CAI on the other hand has almost no restriction, its an open three inch tube from the filter to the throttle body. More air is always better. I was running low 15's with the stick airbox. Now I'm running low 14's with a CAI and a 3.4 pulley. The pulley is great and all but i dont think it is responsible for over a second decrease entirely by itself......