He isn't trying for 4 pounds a month, rather 4 pounds every four months. My calculations are that using 80 square feet, you are going to need more than the 2 lights you suggested, you may want to look into 2 1000 watt lights. (Ideal lighting is 80 watts per square foot, which is 6400 watts for your room). If you have a seperate veg area to grow clones, and can handle a large perpetual garden you can keep plants always being in the flowering stage allowing almost 2 harvests every 4 months, meaning you need 2 lbs per harvest. 32oz in an 80 sq foot area should be rather easy to attain. Perhaps others may see logic differently. I will admit I am not an expert, in fact I am nearing completion of my first grow. I did however stay at a holiday inn express last night. (And have done a lot of reading on the subject.) Hope that helps.