Not sure exactly how T3 effects erection quality, but it definitely does. The thyroid is called the master gland for a reason. There’s literally T3 receptors in every single cell of the body. The thyroid literally effects every system of the body, including the penis obviously. Most of the T3 receptors are found in the brain, and obviously the brain plays a big part in regards to libido and erection quality. Basically since everything in the body is effected by T3, when you have low levels, nothing works properly. But once you get T3 levels optimal, every function of the body improves. May not cure someone’s issues completely, but thyroid should always be the first hormone system to be taken care of, when it comes to hormone optimization. I’ve only learned this recently. This will be common knowledge soon enough, that I can guarantee.