Hey Growmie,
When it comes to your setup, the FC-E6500 might be a tad excessive for a 4x4 grow space.
I'd recommend opting for the FC-E4800 instead. It's tailor-made for a 4x4 area, boasting 480 watts of power. With this setup, you can anticipate yields ranging from 500 to 900 grams from approximately 9 plants, all while saving some cash on the light itself.