I was wondering about this. It might wreck a nicely designed box. Take, for instance, an X Liters box. I don't think it is actually considering the volume of ports and driver, which might be close to 10% the total volume of the box. So, if I simulate a box of X liters, what should I do? a) Add the displacement volume of the driver? b) Add the displacement volume of the ports AND driver? c) Nothing, because WinISD actually considers the displaced volume? I'm very curious about this... sorry about so many questions... but I want to get it right the first time around Javier.