My estrogen levels respond fairly strongly to exogenous test, and I just about always keep my dosage from 400-500mg when I'm blasting (however, you're likely a bigger guy than me). One time I got a concentration at 300mg/ml and started doing 2ccs a week split in two doses (test-e), and actually the increased water bloat and decreased sex drive made me feel like my progress was much worse lol. On top of that the extra 100mg seemed to make me much more prone to acne on my back/shoulders, even after slightly increasing my adex dosage.
So although the question may seem a bit rudimentary, from user to user 100mg could be a fairly large change. I suppose technically speaking, it should increase your ability to gain lean mass. Chances are you haven't "tapped out" your training and dietary possibilities at 500mg, as Bio suggested.