I'd recommend hitting up someplace like http://www.stevesleds.com/">http://www.stevesleds.com/</a> or [IMG]http://www.ledgroupbuy.com/">http://www.ledgroupbuy.com/</a> for a full-spectrum retrofit kit if you;re looking to improve lighting whith keeping the stock look. Ecoxotic keeps revising the number of strips required to light a tank upwards and I was never really satisfied with the results over my 9. Good support, though from them... so no complaints on that front.
But if you've already got an investment in the accessories (power supplies/splitters/one-touch controler or the like) a mix of one or two 12K/445's on one dimmer, a couple 445s and maybe one 445nm/Magenta on another dimmer would work. But by that point you're in the territory of a lot of bigger/better fixtures, cost-wise.