In my experience and Airstream Service's recommendation I have found that pump by-pass systems reduce water pressure and flow to the outlets because of the added smaller diameter fittings. Also you can not use Shark fittings because they are designed for pressure not vacuum and will suck air when trying to seat. Rather than the by-pass kit, I took a length of polly hose, put a valve in it, then added a pump inlet fitting on one end, then stick the other in anti-freeze and pump away. If access is a problem, add a marine deck plate, and cover, 10" dia., to the floor above your pump. Then you do not have to move a whole shelf or floor of thing to get to the system.