At your age 8IU is an excellent dose for muscle mass especially if you are using AAS as well.
Insulin and HGH is a great combo, probably the best combo if you are after gaining muscle and cutting down on fat at the same time. Insulin will force feed your muscle cells with nutrients creating a great opportunity for muscle gains while HGH will assit with fat loss. Not so often do you get a chance to build muscle and lose fat at the same time. The only thing I can say about HGH and insulin is
In time insulin will make a difference in your gaining process, but you need to have patience because insulin is like HGH, the results take quite a while to arrive.
Good luck Timm and let's stop hijacking this thread.
-Gear