You DEFINATELY want some intake/outtake fans with a 600w HPS. I bought one for my closet, underestimated the heat that it would give off and ended up buying a 250w aswell. If you can, try getting a load of CFLs if you cant afford some fans - BobBong gets excellent yields using only CFLs. Im sure you know this already, but they produce hardly any heat and are extremely cost efficient in the long run.