I have tried Bulgarian Tribulus and it works very well. However, what needs to be understood is, trib WILL NOT work with the small recommended doses they suggest on the bottle. While bodybuilding, the amount needed per day is 2000-3000 mg. I have tried with and without vasodilators (Arginine and Citrulline compound works great). Both ways I become a monster in the gym, just more insane pumps when I include the vaso's. I will try and find the research article I read on this a few years ago and post it here. Hope this helps...