I have never used YK11 but going off memory here 5-10 years ago I tried Ostarine, S4, Rad140, MK677, 1Andro, 4Andro, and Epi Andro. The only "unnatural" thing I've run in the last 5 years is EpiAndro. Those other Sarms and things definitely helped me build muscle faster but it was 3 steps...