I downloaded the software and input the specs for the Faital 15PR400. I am new to all of this so please give me both barrels if I say something ignorant. I was able to input most of the data from the Faital specifications. My intention is to either build a 215 box or modify an old Peavey 215 cabinet (as I'm a big fan aesthetically). From what I have read about most peoples attempts with the 215 configuration with this speaker is that a preponderance of people have tuned their cabinets too low somewhere around 35 to 40hz and they end up being unhappy. I'm going to port the cab and assume that tuning it to 55hz might eliminate some of the boomyness. Every time I go into looking at the modeling based on the internal box and other parameters might cone excursions don't look right. They are a flat line and not a curve. I'm assuming that I am missing something somewhere that I was supposed to put in. If someone has a WinISD tutorial aside from the Youtube one by 123Toid, which is decent, but hasn't helped it would be greatly appreciated. I read through JohnK_10's build which seems a bit small. He tuned his to 45hz or so. I think if I can get somewhere between 45-55, I can eq around any issues. I obviously want to limit excursion though. His internal volume was 5.3 cf. What I have come up with was either 6.76 cf or 6.88 (peavey internal volume). I'd likely put something in to separate the two speakers and thus drop the internal dimensions a bit. Any assistance aside from just give up, is greatly appreciated. You can say that too, but I probably will press on.