91 535i 206k i finally got the bass i was hoping for for a pittance. one jl audio 10 inch speaker-one alpine amp-their cheapest one- about 100 bucks-and an $49 speaker enclosure. the bass comes through loud AND clear-no holes cut in rear deck or anything like that.p.s. i do have the optional refrigerator in the center back armrest-that may contribute to the bass getting through-will try to get some pix finally something inexpensive on this beast that actually works