Raw Nutrition, Pump, Non-Stim, Watermelon (470 g)Stimulates Nitric Oxide Production Maximizes Pumps Improves Muscle Fullness How Do You Pump Up? Pump is a versatile pre training formula that can be stacked or taken solo. This stim free formula comes in clutch for the night owls who enter the iron dungeon late into the day, who must avoid caffeine in order to get a good night's rest. On the other hand, Pump can be stacked with your favorite pre workout in order to enhance the effects and maximize