they make you more aggressive so you can get after it in the gym, recoup time is less, HELP'S with muscle and strength. it will not overcome genetic factors, if your biceps don't have peaks it won't make them. their is a couple of guys in my weight /age group that are benching 250 pounds more than me, no drug will get me to that level, you can't set on the couch and eat bon bon's and expect to make muscle all you will get is fat, you still have to put in time at the gym and being on cycle your workout's should be more intense and harder.
just my opinion