That fan may be a bit much for the 400. If it were me, I'd get the smaller size Dayton's (the 120 or 130's?) I forget what the next size down is but it is approximately half of the 265 and I would buy two, one for sucking and one for blowing. I use the smaller size on 3 400's during veg and 2 1kw's for flowering in a small room and you are putting this into a cabinet remember.