nah get the 400w hps going if you can,an insted of 2 plant's grow 4,sound's to me like you got enough room.as your new to growin the more plant's you have the better the chance you'll end up with some smoke at the end,an why waste the eletric on 2 when it'll do 4!!don't over do the fert's(common newbie mistake)whatever the dose it say's to feed on the pack cut it in half,it's easy to add a little more feed than to try an flush the feed out after over doing it!!until u start to get a feel of how much they need that is..anyway good luck an happy growing..love an respect..spliffbuilder.