12 Valves are fun, aren't they? With a few mechanical changes, you can unleash all kinds of power. If you keep pushing the limits of fueling, before long you will surpass the capabilities of the stock mechanical pump. In these instances, or if your stock pump is getting weak, its time to upgrade to a Raptor 4G lift pump. This pump is designed to deliver 150 gallons per hour (GPH) of fuel at 10-13 PSI.