mine too, on cold its about 70-80 psi and about 30-40 when warm...

things to check are oil pressure switch, like you say oil pump is fine

however, your oil cooler is moving oil further around before it gets back to the engine, its route is sump, into pump through cooler pipes, into cooler, back through pipes into oil filter then into the engine, its a long way for oil to flow, your pump may need upgrading to a higher flow rate to pump it round the cooler quicker