VaughnTrue said
as many others have already mentioned, Hemavol is the premier pump product on the market, and has been so for nearly 4 years. Try it out on an empty stomach(no food for 90+ minutes) and 20oz+ water, and you will be blown away by the pumps.
And also remember, being properly hydrated prior to taking it is essential as well. You can't be dry, and expect to just drink 20oz and have it work miracles.. it will work, but being properly hydrated beforehand is essential IMO.
The way I do this, when I want to work out first thing in the morning is.. immediately upon waking I drink 24oz of warm water; i feel it wakes my stomach up. Then I eat something salty, then take hemavol with another 20oz of water.