MY car has the UHF system and I installed the NVX subwoofer. The answer to your question is no. The factory sub enclosure (which of course is greatly lacking in bass) is still there. The NVX system mounts on the driver's side in the hatchback, while the factory subwoofer mounts on the passenger side. You can remove the factory one if you like (it doesn't do much) or you can leave it as I did. The NVX can shake the whole car if you like, I don't like, so I have it turned down so that I can actually hear the bass, even at a low volume. I don't want to turn my car into a boom box with nothing but bass that you can hear coming from two blocks away like the kids that I hear driving by all the time.