Lighting Help

[Chago09]

ok I have a 90 gallon standard 48" tank. I currently run a 6 x 54 watt T5 TEK light system. I want to really grow SPS now so I wanted to upgrade. I have a chance to buy a 400 watt MH 18" pendant. If this was about 18" above the water, would this be a huge upgrade from my T5 and would it be sufficient to grow SPS? or would I be better off buying 2 x 250 watt MH?

My tank has the brace in the middle like most standard tanks. Would this be a conern with the single 400watt?