These steps to access the manufacturer menus only hold until the power is turned off, then all goes back to default settings. Sound quality is mainly lost through the automatic noise control (ANC) feature in the car. You can get some improvement by unplugging the ANC module in the lower center stack of the dash, but real improvement won't come until you upgrade the factory amplifier and use the clean outputs from the radio head unit as input for the new amp. Amp changeout is a pretty big job.