I like several brands of enrgy drinks preworkout. I'll have a RedBull, Xenergy, or Ripped Force if I need a mild boost. If I need a kick in the ass, I'll drink a Spike shooter or a Redline. The yohimbine in the latter two affects me more than any other stimulant in that quantity. I'm used to ephedra/ephedrine and even if I take a 25mg ephedrine tab with a RedBull or a drink with just caffeine as the stimulant, I get a nice boost of energy, but not like Spike or Redline. The only difference in those two drinks is the addition of yohimbine. I will say that unless you are familiar with yohimbine, start out with half a serving, unless you like the mouth-watering-sweaty-jitters.