I don't know if you are trying to maximize space efficiently, but I see a lot of it wasted under the exhaust. Also, it's really best if your flower section has a little more watts than the veg section. Right idea about the flower needing the most room, but perhaps you could use the space under the exhaust for flowering as well. Many plants double or triple in size once flowering is induced. I would use probably 2 600 watters or 2 1000 W.