Some of you may know by now that you can buy OEM tweeters for any standard HiFi Z4 E89 to improve the high frequency sound. Superbow over on the e89 forums originally did this and after I did mine this weekend, was asked to do a write up. If anyone is interested, please check this post out:
http://e89.zpost.com/forums/showthread.php?t=577973
http://e89.zpost.com/forums/showthread.php?t=577973