I found Alpine HIFI system from accessories catalogue. Maybe it is something for upgrading base audio? From catalogue
ALPINE HiFi system
For a significant increase in audio performance and a natural, homogeneous auditory experience. The new, six-channel DSP amplifer has output of 420W, a class D chip ensures powerful bass and class A/B chips deliver flawless high tones and expressive mid tones. Time correction and equalising that accounts for the car's parameters further enhance the pleasure. The ALPINE HiFi system also includes modified mid-range speakers and a pair of powerful tweeters for installation in the upper sections of the front doors. Like the powerful bass speakers under the front seats and the two rear speakers, their high-quality is controlled by two channels.
PDF verion of this catalogue can be found here
and Alpine HiFi is on page 20/21.