My information that 25r-diol is suppressive comes from another thread on here where PA was arguing with Dr.D. PA basically said that if it had any activity with the receptor then it would be suppressive. I am trying to locate the thread right now. This has been a while ago. I will go ahead and admit now that I can't link to any studies that show it is suppressive, I am just going on opinion. I realize that he has competing products and can be real abrasive, but I tend to agree with him on most subjects as no one can disprove him usually. It is also common sense to me that even weak compunds that have anabolic activity(unlike NO), no matter the binding affinity will cause suppression. This does not mean all out suppression like a harsh compound. Its just chemistry in order for a compund to create an anabolic effect through androgen receptors it must bind. If it binds it takes the place of natural test and consequently your body will lower test production. So in all fairness I will admit I can't 100% prove my point, but there is no information that I'm aware off that shows it is not suppressive. Sorry for any confusion I caused, I should have elaborated on my point better before. I will reword it now.
IMO, massfx contains a compound that can possibly be suppressive, and 6-bromo can possibly comvert to 6-bromotest. This is enough to make me believe that a very simple mild pct should be ran. Can a person run this without PCT yes. Would I no.