im actually down grading I had a 4 x 8 x 7 running but gotta go back to stealth I think a 400 watt hps cooled by a 6 inch inline fan will cool it enough I think 600 would be pushing it I had a 600 in a 4 x 4 x 7 and temps ranged from 77-86 usually depending if ac was on and room temp