Hi volume oil pump

25 psi at 2500 is fine. But that better rise as rpm does. Most pumps will reach max volume (and pressure reading) at or around 3000. So your oilgage reads 15-20 at idle, then spikes up to max by around 3K. Max should be 65psi or so, although a factory pump may be valved to by pass over 60. You never really know until it's tested or turning.