I received my 85D a month ago and even tough I love the car, I am not very impressed with the standard sound system. I'm coming from a Chevy Volt that had a Bose System installed which sounded much better. I am thinking about maybe adding an aftermarket subwoofer in the trunk. I have seen that this is done a lot in the US and there are even complete installation packs available. Are there any Model S owners in the Switzerland / Germany area that have any experience with this ? I presume this can not be done by the Tesla Service center... thanks a lot for any input !