As previously stated, diet is a main variable in gaining size. You need to eat like a horse all day everyday. I have heard that Sus500 is a great supplement, but I have no personal experience with it. I do however have experience with Myozene and Synthatrex and they have both worked well for strength and size gains. They are available at prosource.net. A good quality protein powder 3 times a day in between meals and eating peanut butter sandwiches right before bed will also help you increase size.