I have a 97 528i and I have just spent a good part of the day tring to install some new woofers on the driver and passenger doors. But for some reason the quality of the sound is not that good. I get alot of vibration comming from the speakers I assume its the box that holds them that is not suppose to be for anything but the stock speakers. The speakers I bought are Boston Acoustic Rc520 they can handle 25-250 watts. If anyone has upgraded that audio system and has encountered this problem please help me out.
Here is a link For the speakers. http://www.bostonacoustics.com/ProductsPage.asp?ProductID=161&SpecID=4&SeriesID=46