I recently had a local shop construct a sealed fiberglass subwoofer enclosure to fit in the rear door. I am very pleased with the result. It is very inconspicuous and takes up no interior storage space. The sound is awesome. There is no comparison between the sound quality of a sealed subwoofer and a free-air subwoofer. Let me know if any of you are interested in one of these. If enough people are interested I could probably get very good price.