Anyone have any experience with this BavAuto kit? it's part no. INF SWK, called 'Bavarian Autosport / Infinity Basslink "Plug 'n' Play" Subwoofer Kit' and they want $399.95 for it. I don't know much about the stock audio setup in the E34, i just want some more volume (although I'd rather have a more crisp sound at high volume than just outright dBs) and a bit more bass, without spending a grand and filling up my trunk. Is that even doable?