Yeah I'm pretty sure it's as bright in my garden now with the 400w lamp and 600w ballast as it was with matching 600w lamp and ballast. I know for sure something is happening cuz my 400w lamp and 600w ballast set is giving off as much heat as my matching 600w set up did. I know that dosen't necessary mean it's just as bright, but I'm pretty sure I'm pulling 600w by how hot my extenstion cords are and my room temps.