So I've taken this twice, once on a workout date and once on an off day. I think as a preworkout, 25 mg is not quite enough. I't didn't kick in till about 20 minutes into the workout (I had taken it 30 minutes prior to starting, along with the usual fat burners) It wasn't till I really started working out harder that I felt something. By that time I felt great, really wanted to keep going but I had to get ready for work soon. Next time I'll probably take 50mg.
I tried it on my off day, at just 25mg again, and this time the buzz lasted a lot longer. I felt happy, and extremely angy at the same time.
This was not some placebo effect, this was a very noticeable feeling. Had to pull a weekend shift, and maybe I felt a little too focused. Felt some definite rage towards some of my coworkers.
I think I'll try to use this on workout days only in order to keep my tolerece down.