The standard size is 13 cm. Most recommended after market speakers are Canton QS 2.13 or CS 2.13 because of their low installation depth.
The missing bass speakers in the back mean that you have the standard hifi system installed not the optional DSP hifi system.
The whole hifi installation is not that trivial because an amplifier with integrated frequency crossovers is used. Which means even only upgrading the built in speakers is not that simple - especially if you still want to use the factory hands free telephone set.
I recommend using the forums search with the german words "Lautsprecher" or "Hifi" or "Soundsystem". You will find tons of threads.
Hope that helps for the beginning.
|