how many plants?

i have a 2.5x2.5 space.
i have a MH 400 watt with a wing reflector, switching to 400watt HPS for flower.
all will be 3 gallon smart pots.
i'm currently growing 2 autoflowers, but next grow id like to go for 4 or maybe 6 if feasible.
how many plants would my light efficiently support?

The light will support as many as you can jam in there.... But you must keep in mind that you've gotta be able to work in there.

one to two