Yep, free to air is correct, I upgraded to a 10" digital designs in my old BA, took a bit of trimming, original is 8". I'd stick with the better quality stuff. Free to air sub quality is drastically different when compared to the cheaper stuff. I would go with a DLS OA8 or the Image Dynamics ID8, both would work really well, ideally with a larger amplifier but should work ok with stock