The MultiQuip QPT405SLT comes with a multi discharge manifold that includes one 4" and two 3" discharge ports. And while you could reduce from 3" down to 2", not only will you see a reduction in flow (GPM) but you will also be adding backpressure to the pump which could reduce the life of the pump. In addition, pumping salt water with this pump will also degrade the seals and cause a failure within a shorter time period as well as void your warranty. Flushing fresh water on a regular basis will help extend the pump life, if you care to use this pump.