Ok, I have eaten butt tons of bronkaid over the last ten years...
I have supplemented my caffein with coffee and tea etc but I noticed nothing gave me the pump like coca cola while on a stack.
When I was driving a truck and using it to stay awake I really got to experiment with it and found that constantly chugging 44oz fountain coke with the ephedrine could keep me going for days.
I just found a pubmed article explaining why... it was all about the ph balance.
https://www.ncbi.nlm.nih.gov/pubmed/3940208