Here is some trivia for you about caffeine & many stimulants used in common pre-workout supplements. Did you know caffeine & many stimulants are classed as vasoconstrictors they narrow blood vessels & restrict "the pump". Yes this is true & if you don’t believe it simply google "caffeine vasoconstrictor". So many people think stim based pre-workouts have all the ingredients to give you a pump. Well, in the case of caffeine & many others ingredients the result is exactly the opposite. Not what your wanting right?