New set up and Im confused.

I got a 4' wide 3' deep tent lil under 5' tall in my attic. Stuck on what light to use for good yeilds but hps confuses me as im used to using cfls

2 a51 190s

400watt HPS or a 600 watt HPS.. I ran a 400 for years in a 3x2x5 with a 4" inline fan and glass enclosed hood. Just transferred that light to a 3x3x7 and it fits perfect. If that's your only tent I think over time you will be wishing you had gotten a taller one. One day i'll reuse my old tent for veg only.. HPS is my favorite for flower. Although I use mine for veg too works great.. and a 4' t5 for seedlings and clones..
HTG supply has a lot of good deals on lights

Get urself a 600w but also get a 5" carbon filter setup and a cooltube with its own 5" fan,id be wary of using one fan cause then ur pulling already hot,dirty air over ur bulb.but yeah 2 fans and that way temps arent a problem and its more efficient,cooler u get the bulb the closer u can put it to ur ladies

ty