Can someone explain why its recommended (by Tracy) to use a fuel pressure regulator with the manifold vacuum port.  I understand that the vacuum port causes a change in fuel pressure as the manifold pressure changes, but I don't understand why we want the pressure to change.  This seems like it would make it more difficult to tune the EC-2.  What am I missing here?

Also, what is the preferred fuel pressure for a n/a injected rotary?  (I recall Ed Anderson stating he runs 45psi... Is this correct Ed).
Mark S.