400w mh

what do you think a really good yield would be under a 400w metal halide and how many plants and what kind of grow would you do to get maximum use out of the one light? Here is a picture of my 2 widow ladies currently 1 week into flower.

Any comments on my second grow? This is in the 4 plant dwc from stealthhydro.

4 plants should be around the right amount. I have 3 plants under a 400w mh and I could do one more easily. I am using a MH all the way through this grow and the buds are nice and thick. My HPS will be here monday for round 2.