You're worried about Estrogen at only 500mgs? You won't likely need an AI at such a small dose with or without the Mast. I personally don't need an AI until like 2 grams a week so I couldn't imagine using one @ 500....then again, I couldn't imagine only using 500. I also don't think, based on personal experience of course, that DHT's control estrogen as well as some profiles make it sound.