mars hydro ts600 good?

there are many possible factors that play a role in yield.. the environment like temperature, humidity, growing medium, nutrients, watering schedule etc. etc. light is of course also one.. you said you were growing in a 1.3 x 2 foot area (is it with reflective walls, or open?), and the TS600 should be fine for flowering in a 2x2, so no real need to upgrade the light.. you actually wouldn't want to go too strong with the light either (especially when not enriching the environment with co2), so i think you could tweak some of the other factors, and possibly try other genetics..