I tried it yesterday morning, with no other stimulants(no RPM, no morning coffee). I had a very intense energy burst for about 8 hours, but I had some mild stomach discomfort after four hours. I've been having stomach discomfort(stomach acid) on and off from Drive, which I did also use yesterday, so that's likely the culprit. I would be very cautious about mixing this one with any other stimulants within those first 8 hours. I was almost tempted to drink some coffee yesterday morning, b/c the DREN didn't kick in for almost an hour. Its a gradual, euphoric rush. It was good, but I will wait on using the second sample until I've been off of Drive for a while. The stomach problems yesterday, almost have me thinking that I may have some lower GI distress(possible bleeding), so until I get a checkup, I'm avoiding putting myself through that mess again. I have a history of these types of problems(hemorrhoidectomy), stemming from having dysentery in Afghanistan(poorly cooked goat meat and pita bread

).