what size light?

I've got a room 1mx1mx1.5m. What size light should I use and extractor fan? My mate has same size room with a 400watt air cooled light, but I heard 600watt will give a bigger yield, so I'd like to use the bigger light. Could I use a 600watt non air cooled and use a bigger extractor fan? or should I go for an air cooled 400 watt? or 400watt non air cooled? Not sure what to do :/ any ideas?

600 watter. Always go big to grow big with lights and air.

I use a 1000w HPS in a room of similiar size. One 6"inline fan and ur good. Go big or dont go at all.

LED would be cooler, but I am not sure what your budget is. I switched from HPS to LED and I love them, no more heat issues but I did have to put a heater in winter months because it got a little cold. This is my 1st grow with LEDs and they seem to grow a lot faster. I have a 4x4x8 closet and I use a magnum 357 which is 180 watts and 2 90 watt Sunshine systems LEDs. I replaced a 600 watt and I save 220 watts and I think they work better.

LEDs expensive not going for them lol... I'll more than likely go for a 600watt light with 5" extractor