I'd like to chime in here. Running my Homebox XS, 2x2x4 for over a year now. Grew with flourscents until this recent grow and switched to a sunsystem 150w HPS, not remote ballast. My first ever grow is in my sig under my journal. Broke my camera last year and havent been able to share with you guys.
Anyways I got 3 girls in there now under the 150w. They're supercropped (Bent at 90 degree at that) and take up an effective growing area of like 1.5x1.5ft. 4th week of flowering and the buds look way bigger than cfl. Time will only tell how much bigger.
I've had to keep the front open for the majority of the day to keep temps below 80. I went to the store yesterday and bought a cheap inline fan thats rated at 80cfm (100 max it says) along with ducting, duct tape etc. I also bought materials to build a filter. Well, without the filter on there the tent still reaches 82-83 while ambient is 72. With the filter on it pushes 90... The grow room is 16cf and my fan is 80cfm; 5 exchanges per mintue. Shouldnt this keep things at least 5 above ambient? Is the ballast making THAT much heat on 150w?? Will it make a big diff to remote the ballast