600w will increase your yeild... for fan get may 2 intake like u have and get a 8" scrubber for back or side mount for exhaust . thats my input... how many plants u wanna grow? im in the planning stages how a closet just like this. check out this cab and the others... u should b able to get some great ideas for what kinda air flow.. like 265 cfm blowers.. Jumbo Stealth Grow Cabinet v2.0 w/ Tek Lite T5 (8 Tube) Floro System & 5-40 Plant Aeroponic Hydroponic System w/ Co2!!