Robospaniel

Hello. I have recently become the proud owner of a 2009 3rd gen outback 3.0rn and I love it. However unfortunately it does not include the optimal Harmon Kardon audio system or cd changer and the only thing that disappoints me about the car is the poor performance of the standard speakers. The head-unit has a subwoofer option but it doesn't appear to have one. I have done a little research and have found out that the factory head-unit is very difficult to replace so I would only be looking to replace the standard speakers. Has anyone here upgraded their speakers and if so can you recommend some for both the front and rear doors? Any advice on mounting accessories and wiring would be much appreciated. Thank you for your help. A confused new Scooby owner.