Hello my friend first off you dont want [gdf-8 because this is the muscle limiting protein itself ] now with that being said myostatin propeptide or the anti-body for gdf-8 will be what you need to do your research on to compare to follistatin.
Thanks again, Im trying to read as much as possible on these and some things just get confusing and it seems like you are just rereading the same things over and over. LOL