I asked my wife, an ICU nurse, about this combination of drugs as a concentration enhancer/weight loss tool. According to her, use of ephedrine in anything but a medical emergency is a really bad idea. Wrong dosing/accelerated uptake due to other factors could mean a heart attack really really easily. Probably you already know this, but I can't assume.

She also told me that, if you are going to choose a strong stimulant, there are a lot better choices than ephedrine (sorry, forgot specifics).