^^^
LMAO
AleX-69 put it as simply as you might ever see it explained, good job bro. Why do the bigger guys all have guts? When did guts first come to the scene? With GH? Nope. With insulin! Because insulin is only really worth it when used with GH, *BECAUSE* it makes more IGF-1. And that grows the guts and all organs. As well as muscle, obviously.
As for site-specificity: Long R3 IGF-1 is designed to be a systemic drug. But by injecting in a muscle that has its receptors greatly upregulated by exercise, we diminish that systemic effect because more local receptors will take it up, leaving less for organ growth.
So yes it's a systemic drug. But yes you can diminish its systemic-ness, and that is a GOOD thing. Now if you're gonna pin 100mcg ED, then it will be pretty systemic no matter what you do because that's simply a huge amount, which SEEMS to be needed when you pin at non-optimal times, but isn't needed if you pin when the muscle receptors are at their max.