How many plants could i veg under this t5 ?

http://www.ebay.com/itm/T5-Grow-Light-2FT-4FT-4-6-8-Bulbs-Fluorescent-Lamp-Bloom-Veg-HO-Hydroponic-/290901486749?pt=LH_DefaultDomain_0&var=&hash=item43bb146c9d

i have a 4 x 2 tent and im oing to make a seperate veg chamber out of foam and plywood .
how many plants could i veg under this . would it be good for that size tent ? if not what should i upgrade too ?

I use a 6 tube T5HO fixture for veg. (2x2700K and 4x6500K) mine is a 5ft fixture as I got it for free at work, but run the same watt as a 4ft

and Im able to veg 4 plants for 8 weeks easily, sure I could fit 8 plants in there, but at week 3-5 it would be pretty tight, not just the canopy but also pot size`s

I would say 2 plants under a 2footer and 4 under a 4ft if you want to veg for more then a few week and a minimum of 4 tube`s with 6 or 8 it will be more easily to keep em under the light and do a lot of LST or topping etc.