I just installed a FPR. I put the pressure at 40 no vacuum. The pressure dropped at 30 with vacuum on. Is that ok. I heard so people running no vacuum... What is the benefit of doing that?
Running w/o the vac line attached means the regulator does not vary pressure depending upon fuel needs (very crudely stated, manifold vac is inversely proportionate to fuel demand. E.g. at idle, you have high vac and low fuel demands. At WOT, there is almost no vac and high fuel demand).
Running without the vac line attached can mess with the puter since it expect a pressure delta between WOT and idle [static] pressure.
Your pressure readings are alright - I would have hoped for less difference (like a 5-6 PSI difference).