Primo & mast have really gained some popularity these last few years. I thought mast was pretty weak when I ran it at 400mgs weekly with 400mgs test. Could it have been under-dosed, sure its UGL. All the guys I've seen praising those 2 compounds are all running GH with it. I'd compare 400mgs mast to 100mgs test added to that cycle. It was pricey also but I wanted to see what all the hype was about.