Are you sure the boost gauge is accurate? 14 psi on a 4.6 is like way over 500 whp.
No it doesn't, not necessarily. It means you have a restriction. The blower will pump x amount of air at a given rpm. If all that air gets sucked in the cylinders there is no boost and lots of power. If you restrict that air and it doesn't get into the cylinders you get pressure or boost. So given the same supercharger speed the less boost you make the more power you will produce.