the front speakers are 13cm or 5.25" to remove the panel you have to remove the plastic thing on the side they have plastic round things you have to pull the interior circule and then te other thing there are like 4 or5 you remove that and then you can remothe the other thing look at this picture
look number 5 look at this page
http://bmwfans.info/ there is everithing about every bmw new and old ones every part accesories etc