welcome to SC..the MY03 9-3 sedan was not designed to fit aftermarket units ,due to the fact it use the MoST fibre optic loop for the audio and other systems..what you see in the dash is the control panel,the actual ehu is located behind the acc/mcc control panel.1st port of call would be to upgrade the speakers..sizes are dash l/r 3.5" rear shelf 4" and doors 6.5",the dash/rears are 4 ohms and the doors 2 ohms..