I saw a lot of people ask about audio systems for base models, so this is the setup I had in my previous Impreza. I also had two 180w Alpine Power Packs amplifying kicker speakers. My new Impreza has Harmon Kardon system so I just installed my amp and sub, but I definitely got better sounds quality, and loudness with the old system. No complaints with the Alpine sub and amp, with the Harmon Kardon though! All but the head unit can be purchased through best buy
Alpine Sub and amp
Jensen CAR100 10.1 IN screen
Alpine Sub and amp
Jensen CAR100 10.1 IN screen