The stock premium system have really good and impresive speaker for that kind of car, the problem is the lack of power and the crossover of the factory amp... when you will remove your door panel and see the speaker you will know what i mean
that said, STOP listening to MP3 and SAT radio and get real CD and you will definitly heard the difference, and like OGB said, if you ever got in a 2007- impreza its day and night