A 'cough 'from the engine on take-off at Geraldton would have been easily overlooked as it returned to full power and take-off and climb were normal. What would have focussed my attention though, would have been the power decrease at 1900 ft. My training was that the tanks were switched ASAP that there was any drop in power, regardless of altitude. The aux pump goes ON about 2 secs later. The POH specifies tank change as point #1 in the emergency response, and it's always restored power for me anyway. This includes where I've intentionally emptied a tank, eg, the AUX tanks of a PA23, 30 or 32. It seems to take forever for the engine to roar back to power, but was probably only < 5 secs. (FAA Certification says up to 10 secs OK). I suggest that training in PA-28 aircraft should include a fuel starvation review - at a safe height and location of course. It's a fact that many/most student pilots never actually do this stuff, similarly flying with a stopped engine. We do it for loss of electrics, loss of flap function - so why not for loss of noise?