ive been wondering this too, so far i just started taking an e/c stack, i took 25 mg. ephedrine, 250 mg. caffeine first thing in the morning for one week, and i am 4 days into this week taking 25 mg. ephedrine and 250 mg. caffeine twice a day, once in the morning and the other at 2:30 (30 min b4 workout). i dont feel nething, no jitters not "high" feeling, the only thing i notice is that i can stay awake much easier due to the caffeine. at the end of this week i plan on taking my dose 3 X a day adding one in at 12:00 and taking 50 mg. caffeine out of the dose (so 200 each time) as i am gonna go from mini thins (the 25 mg. ephedrine alkaloids and 50 mg. caffeine) to bronkaid (25 mg. ephedrine sulfate) for the source of ephedrine. if i dont feel nething from this, do u think i should try xenadrine.