Although mb quart never claimed this would fit the e83 x3, I pulled the trigger anyway because all the speakers mounting spots looked identical to the stock ones in my car..

I learned that the subwoofers were a perfect drop in fit. Just had to remove the seats and the sub grills in the floor, undo 4 screws and wire harness... I had to crimp two u terminals onto the wires in place of the harness. But that was it. Super easy!

The door mids and tweeters were a totally different story!!!!! while the mounting screws looked similar in layout, they were not in the right places! Also, the door panel hole the mid fits in was too small. To complicate this I wanted the look of seeing the cones thru the grill - this required some moderate to heavy modding on the door panels. I removed the thick felt and 1/8" foam that was in between the speakers and the grills (this I believe was not helping the crappy sound btw), I then dremeled the hole bigger in the door panel. Because I wanted to see the cones thru the grill and the cones actually have "mb quart" silk screened on them, the logo needed to be perfectly horizontal when mounted. The three mounting ears on the speakers were in the completely wrong position to accomplish this. So I basically dremeled three indents into the speaker housings so the threaded fasteners on the door panel keyed into them. I then used washers and the factory nuts to hold down the speakers. The tweeters were also difficult. I got them to snap into the factory holes but had to Drexel apart the whole housing and leave material that would catch on the spring tabs in the door panel. It came out fantastic, and sounds amazing!

Keep in mind though. I had to do these mods because this system was not made for the e83 although the subwoofer was a direct replacement..