my uncle's friend had a rot he used to juice up w/ test, how much/how long i don't know, but the dog was HUGE w/ a ridiculous neck. he used to play w/ a bowling ball in back yard, pick it up w/ his teeth w/ holes and fling that shit through the air. he also humped the shit out of my uncle's leg and waist once, uncontrollably, and blew it's load all over the place. true story. just thought i would share. but to answer the question i would give my dog, or wife's dog i should say, a lean bulker, maybe alittle test, tren, EQ and var. is that too much for a 4lb yorkie though...?