GVT 2000?

As soon as rugby season is over I’m looking to put on some muscle. For anyone who has tried GVT 2000, how did it work out for you? Did you do it for the recommended 3-4 weeks or change any of the exercises (like adding a set of one exercises and taking out one of another)?

I’ve been using it longer than 4 weeks, simply because I havn’t found another program simple and effective enough to switch to. Then again, since I’m a teenager and new at training(kind of)I can spend more time on a program that older people.(So I hear anyway.) But my experience has been a good one. I switched a few exercises around a bit everyonce in a while to keep from getting used to the same old stuff. I’ve seen great gains though.