2 T5 bulbs being driven by a 660? For one thing the 660 is overkill, it can drive 16 foot of flourescent lighting. And you would expect to get about 80-85W out of each bulb, so your going to be pushing more like 2.8wpg and if you happen to be also using IceCap SLRs your going to be high tech I'd say, those things are powerfull (both the overdriven T5s and the SLRs). I am running 4 T5 bulbs over each half of my 240g powered by a 660, and I only run all 4 for like half the day. You'll also need to make sure you have good cooling on the bulbs, icecap reccomends fans blowing directly onto the bulbs since they get very hot. Or else their life will be shortened. Good luck.