Hey smokedat, I'm just jumpin in onthis thread, but the plants lookin much better already. You will notice a huge differance with the HPS. My last grow was kc36, I vegged with only floro tubes(its all I had) then "aquired" my 1000w hps. I made an insanse improvment with my plants. Like sunnyd said, keep it alittle farther away the first few days, so they can get used to it, and you can figure out what will be just right for yours so they don't burn. I would deffinitly be using nutes on the older plants, and on the others once they are about 3 weeks old. Start slow, and build your way up to more, once you see how they like it. DON'T USE MIRACLEGROW! Do you have a local hydro shop, or garden center? If so try to find a well balanced organic nutrient. It will boost the size of your plants, and organics tend to provide a nicer flavor in the end. If you have 4x4x8, you have room for a, or some good size plants.
Heres a thread that offers a great method to increase yeild with less plants, in about your size area.
https://www.rollitup.org/indoor-growing/90011-4x4-600w-scrog-3rd-wk.html This guy has his shit straight, my next grow will likly be this SCROG style, with AK47 plants, my goal is 1/4lb per plant, in about a 5x5 area, with my 1000w light. I think it should be easily attainable.