Massive Growth is a different kind of pre-workout supp'. I've used Animal Pump and Black Powder before and they have a real caffeine like effect combined with good pumps but MG is different. You don't get "the rage" that you get with some supp's but what you do get is a complete mental focus. You feel like you're in a zone and the mind muscle connection is very strong. As I am going through shoulder rehab' at the moment and my weights are still light I can't comment on strength increases but the pumps are good without being insane.
The one thing you do need to be careful is the size of the dose. As BtB said after my first couple of dosings I was ready to drop the supp' altogether. The first time I took it I used just over 5grams (which I thought was half a scoop but they sent it out with the wrong sized scoop. I'd been told but had forgotten so it's my own stupid fault). The first thing I felt was the tingles. I knew this came from Beta Alanine so didn't worry too much but by the time I got into the gym around 25minutes later the skin on my face was burning red and very tight, there was rashing on my neck and shoulders. It calmed down within 45minutes of taking it and was back to normal within 2 hours. Second dosing was around 3grams but I don't think I'd had enough food (or maybe I was just nervous following the previous day's effects) and felt really jittery. Since then, however, I have been taking 3-4grams for the past couple of weeks with no ill effects at all.
This is definitely a supp' I would recommend so far. My favourite thing about is the "calm" nature of the mental focus which is particularly important as during the week I am downing this at around 7pm and want to be able to sleep at 11pm. With MG I feel alert but can sleep over it whereas with the other more caffeinated supp's, I would be lying in bed buzzing for hours trying to sleep.
If anyone has any other questions about the supp', let me know.