Yes . Testosterone is important to keep you men ( sex drive , energy, mood ) but when comes to grow really big IGF levels are the way to go ( the higher the IGF the bigger you can get ). To have high IGF you need HGH + Slin or MK677 + slin , or even better real IGF . Pros like Walker are not so freak because of using grams of test but yes alot of hgh with some slin ( HGH is the #1 drug to be a top bodybuilder )