I don't think you would get much more positive effects from 300mg's than say 80mg, but you will get more sides and stress your body needlessly. You might not notice it now, but soon enough it will catch up. Highest i ever went was 40mg (top notch) and that was with nolva and still awesome.
PS. I've been involved with Powerlifting for as long as i can remember and we are pretty honest to each other. I've seen more than my share of 'generation xbox' kids, throw a sissy fit when they realize, it really is more than swallowing pills and injecting everything...
Hard work, is called hard for a reason.