Do you have tweeters inside of your door mirrors? Just trying to ascertain whether you have the base stereo or hifi system. I suspect you have hifi as your car is MY2006.
The speakers/amp are certainly the weak link in the OEM systems. The OEM HU can be used to create amazing systems, and has been by many members.
I also looked at HU replacement but I went off it as i found out that I would've lost most of my idrive functions, and i dont think you can get software updates from BMW as well. Plus i like the OEM look.
Ohlins R&T with custom Swift rears, diff lock plate, monroe upper shock mounts