Yeah, I use EPH833 as part of my pre-workout stack. I stack 1/2 cap with 100 mgs of caffeine and 2.5 mgs of yohimbine. That works very well for me. Never tried it all by itself as I'm looking for the fat-burning effect in addition to preworkout stimulation. I have taken full caps with 200 mgs of caffeine and 5 mgs of yohimbine, but that was a little much for me to tolerate in one dose...