One big pump like the Walbro 400 would overrun the regulator at idle, this way I can keep the stock regulator, and on my setup I really don't need the second pump so no worries about the second one failing. The single Walbro was more than sufficient at fueling my setup. This setup is almost identical to what buschur makes and runs along with hundreds of people that run his kit, so I'm not worried about a Walbro failing they're pretty reliable pumps. Having the second pump will come in handy next spring when I switch to corn