That's only 48 watts to cover 8 square feet. It doesn't matter what kind of light you use, 48 watts is nowhere near enough to cover that footprint. T5's need to be packed in pretty tight over the entire grow space somewhere around 2 inches apart to get really good results from them for either veg or flower.As far as power goes, I would try to shoot for closer to 400 watts of whatever light to do a 4x2 space.
