Building a grow space..

I'm currently in the process of building a grow space. I'm going to build a 4x4 grow space in my basement... Ceilings will be about 8 ft high. My question is, will a 400w MPS lighting system be too much for this size space. I'm looking to grow between 4-9 plants with soil... I'm going to be installing a dual computer desk fan with thermometer to control the heat & ventilation. Thank you in advance.

a 600w is your best bet although im not sure on the exact light foot print, i know a 1000w has only a 5x5 foot print. and as far as 9 plants, a 4x4 will fill up quickly if your plants are bushy at all 5-6 will probably be you maximum square buckets are also beneficial in confined areas where plants will be closer together

Well I was thinking of implementing a second 400w system but I thought that might be overkill.. I figured a 4x4 space should hold @ least 9 plants. I was told elsewhere that a 400w hps system would be sufficient for a 4x4 space & about 13 plants..

I flower in a 2x4x7' space and use 2x430 HPS lights so two for you isn't overkill. A 600 would be fine as well.

I think 4 plants would be ideal. A buddy has 4 plants going in a 4x4x4 space and they fill it in nicely with only a little competiton for light.

Ok... After a little more research & Advice I'm going to start much smaller. I'm going to convert an old cabinet into my grow box.. Dimensions are 2x2-1/2x6... I'm going to run a 400w MPS & I picked up a cool AV cabinet Fan that came with a digital temp gauge. I'm thinking the fan system will help with ventilation & temp control. I'm going to shoot for 2-4 plants.. I'm taking cab apart now to disinfect , retro fit fan & ventilation ports.. The inside of the cab is flat white color but will that do or should I buy reflective material to put inside? I'll try to post step by step pics once I figure how to post the pics. Still open for any advice on the setup.