My brothers bose sub stopped working. I pushed to cone and it started playing. So i'm sure its blown. He has a 2000 Nissan Maxima. I checked crutchfield for a replacement. They offer an 8 "10" 12" replacement. Has anyone ever replaced one? Whats in there an 8,10 or 12? Is it a 2 or 4ohm? Will the replacement need to be free air?