I would be looking to pull 4 lbs from 2000 watts. I am OK with 3.5 but 4 is the mark for me.
. 4 pounds off only a 2 light room? lol. You should be happy with just 3 pounds bro. Unless your using multiple lights,, like 4 or 5,, you proboably wont get 2 pounds plus per light. The plants feed off all the lumens in the room when there is a high number of lights. Otherwise,, you are just asking for 2 much.