Just to clarify.
Most fuelpressure regulators I've ever seen, will increase the pressure when there is no, or low vacuum !
When I went to school, the story was, for every 2 inches of vaccumdrop, the fuelpressure would increase by @ 1 pound.
Makes sense, when your cruising ( high manifold vacuum ) you need very little fuel, hence low pressure.
When you " get into it " there is low manifold vacuum & high fuelpressure.
