I have been looking at new pre-workout supplements and I keep coming across reviews that mention 1,3 and 1,5 mixtures, but none of the reviews ever explain what they mean. I assume that they are some mixture of stimlants and I was wondering if anyone could shed some light on this subject for me. I had been using GNC's Ravage, but recently switched to ACG3. Any thought on either of these pre-workout powders would be appreciated as well.