okay, 'yes' on the IGF-1 & hyperplasia
on the Hex: endogenous IGF-1 levels (that is, your body's own natural production) is the result of Growth Hormone's action in the liver, and so IGF-1 depends on endogenous GH levels.
Hexatropin contains GHRP-6, which is a GH secretogogue; that means GHRP-6 makes the body secrete GH; if it's already secreting GH, it apparently makes the body secrete more of it. That means more GH, that means more IGF-1 coming out of the liver, and THAT means more hyperplasia (clinically & anecdotally, it means more than just that, but you asked about size.
Hexatropin also contains hexarelin, which is an analog, or variation, of GHRP-6. Hexarelin has been found clinically to stimulate GH secretion 'much more strongly' than regular old GHRP-6; there's a lot of other cool stuff about hexarelin's effects; I've really been surprised by how much research I've found on it specifically. It has effects on brain & heart health & apparently the ability to 'restore' GH production levels in GH-deficient individuals.
So, again, still MORE GH, leading directly to more IGF-1, and all the good stuff that comes out of both of those. And more muscle cells.
does that help?
(it occurs to me that I may sound like a shill for IBE. For the record, I have bought with my own money ALL the IBE products I've ever received, including tropins; they have not offered me anything, I have not asked for anything. I'm clean as a whistle!)