I am taking my 2000 528iA in to have a few car/key memory items set (auto lock doors, get rid of chirp when locking/unlocking) and through browsing the archives I have seen many references to having the DSP set to MAX and the Frequency Shift set to 40 Hz. Everyone that does this claims it sounds better, but no one describes HOW the sound changes. Can anyone tell me what the changes do to the sound?