Usually the pumps aren't the cause of loudness, the mounting of the pump is. You can isolate the pump by putting in on top of a piece of plywood and putting rubber under it to quiet it some.
Also, what many people think of as loudness when the pump runs, with their head stuck inside the water compartment, is not that loud inside the RV and many of us use that sound to tell if the pump is coming on periodically when not called for. If it does, that tells us there's a leak somewhere. If it doesn't come on periodically there's no leak. So it's acting as a 'Tell-tale'.
