4x4 will be fine.. As long as the 400W will really do well in that space. I think im gonna go w/ 1 400W MH and 1 1000W HPS to start..If the 1 400W MH seems like its not up to snuff then I can always add another 400W MH and it wont even still had cost as much as the T5 set alone.. And I would...