As far as Epehdra, goes, you could run, 25 mg, if you have a real high tolerance, go 50mg.With Caffeine go 300 mg, 350mg tops, then no more then 100 mg of Aspirin.Now Yohimbe, if its real HCL you need 12-16 mg tops, 15 mg is optimum dosage.
You have to watch you Yohimbe because it can make you jittery, and make you feel weird.
To make this stack really crank do this
25 mg Of Ephedra,
75mg Of Synephrine
100 mg of Caffeine
15mg of Yohimbe
then add 20mg of ginger to raise your body temperature