The amount I take is miniscule compared to what they shot him up with. I believe it helped me tremendously on the last 3 job interviews I had... got hired every time. The secret is self-control. Easy to abuse and get addicted (like so many on here seem to be). I had workout partners who could not train without it... they have many health problems now, mainly due to ephedrine abuse.
I have only used pseudo-ephedrine with caffeine and even that works very well for focus and energy.
I have tried Ritalian, but was not impressed and found even pseudo-ephedrine to be more effective.
However, what did work very well was Modafinil, it gave the clarity and focus without the edginess of pseudo-ephedrine.