I'm only on day 18, so far the combo of s4/GW has been good....endurance is way up, I think I'm getting stronger as well.
My wife grabbed my arm at the gym today and said it is getting harder...she doesn't even know I'm taking sarms....
s4 will definitely add a lot of strength and most definitely provide muscle hardening... s4 is definitely one of my favorites.. also it provides excellent vascularity, especially the leaner you are