I got 80w goin for me right now for 4 plants.. so I'm to assume that i'll get 24g appx for each plant(80w x 0.3g), or 6g for each plant (24g/4plants).. ??? is this math right?

I'm tryin to get a few 50w HID MH bulbs.. does anyone know the yield-power those bring, as opposed to the CFL n HPS?