What light would be best for 4 plants

I have 4 plants going and i just started them. Right now they are under a 108w Florescent light, and when they start budding im putting them under an HPS light. What output HPS would be best to cover 4 plants?

Also, what is a good material to surround the plants with, so no light is wasted?

250 watt HPS is good...400 watt HPS is better for 4 flowering, FEMALE plants...:thumbsup:

Flat white paint is good on walls..(like in a closet)...mylar is a PITA