The next phase is about reducing estrogen and giving you another pathway to both boost testosterone and increase sex drive. Androsterone is a natural metabolite in the body that reduces estrogen which increases testosterone and is proven to reduce aromatase (that nasty enzyme that turns your hard earned testosterone into UGLY estrogen. It also is a 5aReduced androgen, which as a class have been shown to be potant neuro-stimulants. Neuro-stimulants don't get you wired, they make you more alert, aggressive and intense. So, Androsterone has published studies showing that it can reduce aromatase and increase mental intensity.
So no it would not shut you down. Thats why its so good for PCT.