Whenever you combine two stimulants together, you get an amplified effect - a much stronger stimulant effect then either drug can provide on it own. It's simple. It's a dangerous practice and I advise against it. It can cause serious heart issues, arrhythmias, high blood pressure, high heartrate, higher body temperature, dehydration, and other nasty PNS effects - which can lead to stroke or heart attack.
Be very careful.
Closing this thread as it is totally self-serving and will not lead to substantial or further productive discussion.