For the record, the only "real" use Winisd/BBP, etc. have is your ability to see what changes what, not so much how the box will actually sound, if that makes sense. Once you drop a box in a car EVERYTHING changes so anything winisd tells you is pretty much irrelevant. What you can use it for is to play around and see how changing stuff like box volume effects the response. Then, using that, you can design the box from there.