Is there a slight drop at around 4k? Some pumps will cavitate between 4k and 4400. The reference at 4k is what made me curious. There are non-cavitating pumps out there by most of the aftermarket if your worried or someday want to swap it out. 30 psi isn't that bad at 4k but you didn't fill us in as to what the readings are at other rpm's. If its bearings that your worried about it'll show with idle pressures dropping or fluctuating.