Well you already have 600 watts of warm and 500 of cool, I would go more towards the warm (red) spectrum if anything, I think that's PLENTY of light for a 4x4 area (more than I use)... I don't know why people are so against CFLs... they run cool, don't need ballasts and cost way less to run per month... No offense to anyone, but it seems us CFL growers have been branded idiots, but I have seen too many successful grows with T5 and CFL to make me believe they suck...