upgrading from a 400w to a 600w got some ??'s

depends on what you were trying to do with your 400w. if you had 4 small plants under your 400w in 3 gallon pots and they only got to 3' by the end of flower then you probably won't see any improvement at all. bigger is not always better. if youare trying to grow a few plants more then yes; but growing 1 plant under a 400w and another under a 600w will not make a difference in yield. unless height becomes an issue.

You are increasing wattage 50%, that means you can get the same wattage as before on your plant from a longer distance
from the light. Means you can fit more plants under the light. My brother went from 6 plants with his 400W set-up to growing
9 plants under his new 600W. If you have less than the maximum number of plants flowering, then it's a good idea to get your
plants as close to the light as possible without burning. Figure out just what size area receives the full benefit of your light then
move the plants up until they fill the maximum coverage area. That way you are getting as much possible benefit from your lights.

Good luck, BigSteve.

yeah... I don't think it will increased bud size or anything. It will expand the area that you can grow in. It all depends on how big your pants are, but with a typical 400w setup you can do 4 or 5 plants. With a 600w setup you can go up to 9.

If you were growing 9 plants under 400 watts and are now going to grow 9 plants under 600 watts... it would probably increase bud size. But, that would only be because you would have been doing it incorrectly before.

basically all more wattage means is that more plants can grow successfully under the lamp.

eggcellent this was the info i was looking for thanks much guys