Hello, At the moment I drive a 1 BMW with a subwoofer called below in a trunk extension. But in business I am now unfortunately dependent on a “case room” – therefore out the thing On good bass I do not want to do without. under the seat “gammeln” still the original 16 cm basses (cheapest soundsys) unconnected around. From PDFs I have taken that they are built only by an adapter ring and upgrade is possible up to 23,5 cm. Volume is enough, because an ansc Now I am looking for very good subwoofers in this size order. The problem should be the following: The BMW parts do not have the magnet behind the membrane, but rather in the funnel of the membrane, so that the installation depth is minimized… Are there comparable products also from third-party suppliers?! gruss, dognose