Like others have said, I pulled out the cheapie B&O sub speaker and installed a seperate 300W sub amp and a JL 10" in its own box in the trunk. Yes, it takes up a little space but not much. The difference in sound is worth the real estate. I left the old B&O speaker out so the bass could "vent" through the grill opening. Now it sounds like a proper high end stereo, although it has to have a separate bass control up front, which is steadily hidden. Lots of examples out there of that being done. I would have loved to put it in one of the trunk wells, but I was quoted $2,400 for the equipment and manufacturing the fiberglass box to fit in the right side well. The manufactured JL box sounded pretty good after that! Good luck!