Wow I replaced my microfilter yesterday and my air works 500% better. I'm still new to my car and I'm learning. So the microfilter went unnoticed by me for a few months... a few years at least from the previous owner. So this is a reminder to anyone who hasn't changed it lately. Just check my pictures and see how bad it can get.
<img src='http://www.bmw-forums.com/forum/uploads/photo-3078.jpg' border='0' alt='user posted image' />
'93 325i 5 Speed
-2 12" MTX subs
-16" Double Spoke Rims
-OEM Clear Corners and Tails