I personally am extremely sensitive to estrogen. I guess on true trt, one might not need an ai but everyone's true trt is going to vary. There are guys out there on no exogenous test, yet they still have high e2 levels and need an ai. I've come to realize that I can't run high doses of test and by high doses, I mean 500mg/week. What I believe to be the biggest culprit, low shbg. Last test it was a 21. Causes large spikes in estradiol. I can go from too low e2 to too high in a matter of days. I have started using test u, which has an extremely long half life and hopefully on a low enough dose, 100mg/week, I wont need an ai and only have to pin once a week, not this everyday stuff I keep reading about. Only time will tell. My point, I dont think ai's are bad, at least not aromasin. Not one study has shown it to have a negative impact on cholesterol, the most common downfall to ai use, but actually a positive effect if anything. Really just boils down to finding the right dose and not overdosing. Estradiol must be controlled within reason.