To the OP,
This is a really nice stack. I'm pretty sure one of our reps from another forum has ran it more than once with pleasing results. It's a pretty sick stack.
Hyperdrol X2 works to safely decrease the amount of the aromatase enzyme in your body. This enzyme is responsible for converting androgens to estrogens. This not only increases testosterone by preventing conversion to other hormones, but your body likes to have a certain testosterone-to-estrogen ration so it actually increases testosterone production in attempt to maintain this ratio. The end result is more total testosterone.
MassFX has a few different mechanisms of action, so I'll speak just briefly one these. First, 25R-diol gives you "more fodder" to make testosterone. You make your testosterone from cholesterol, but it also forms progeserone and cortisol through this mechanism as well. 25R-diol works similarly to cholesterol in that the body can use it to make androgens, but at a much higher affinity for producing testosterone.
Secondly, our divanil binds to the SHBG (sex horming binding globulin), deactivating it. I love that word, globulin

. SHBG binds to and deactivates testosterone. Your total test might be good, but SHBG has been known to deactivate over 90% of it, leaving only a small amount of free test. With the hyperdrol and 25R-diol, we've increased our total test, divanil lets us make some use of it by freeing it from SHBG.
Now onto X-factor. Arachidonic acid is used by the body to produce prostaglandin 2F-a and other prostaglandins. This process is both chemically and mechanically limited, so you should take the time to stretch your muscles every day, as this will assist in the products effectiveness. These prostaglandins will jack up the rate of protein synthesis, from LH (hormone used to produce testosterone) to IGF-1.