your diet and training is the rule for progress, steroids it just speeds up the process,
discipline with the basic estimulate more AR, more AR better results with any drug, so in the past of years you became better and better.
but 300 to 500ng/dl you will not see significant changes, keep your test at natural levels 200-800ng/dl dont increase your modd, performance etc, any level in this range for me it doesn't pay to stay pin