.........It is behaving like it is breathing better with less restriction....... Picture a garden hose that is open...... Now put a nozzle on the end that has a small tip...... with the same amount of water coming from the hose it will have higher pressure with the small tip. With larger valves, ports, and Cams the engine moves air with less restriction and can not build as much pressure with the same volume of air moving through it ;-)
The smaller the valve and less it opens and the less open time the more pressure you will have.
