2-400watt mh

My question is how many super skunk plants can i comfortably grow under 2 400watt mh lights if space is not an issue.

Start smal, let´s say 10 plants, then work ur way up to about 20...imo i´m running a 400w hps over 7 plants at a time and i could fit at least 5 more to the count without loosing to much lummen/plant ratio...remeber good light reflection is a key to success....Peace