Arginine always improved my pumps. I know it lacks certain scientific data to support increases in nitrous oxide and a lot of people conform to the forum's status quo by saying it's junk. I agree that generally it doesn't help one's overall progress, but it does give me increased pump when I lift... I wouldn't buy something just for increased pump. Something that increased stamina would be far more beneficial... Most people shouldn't need supplement help for pumps, unless I suppose the idea is to momentarily appear larger than normal outside of the gym.