oops, when you fit sub in the boot, you will need to cut to allow sound through, those cars are sound proof man! there's no space under the seats, you don't want to cut the doors, and yes you need bass, Audio bank amp is a good option with a 10/12'' sub, get a splitter and keep your std radio. I installed this in my E46 325i and its amazing. Not to big and not to small, just perfect!