for sound quality, there's no doubt that a new deck and new amps will sound clearer. the higher the RMS watts, the cleaner and crisper the sound. However the factory system on the G20 really isn't that bad (some of you will say otherwise). If you did replace the speakers, it would sound fine, but don't expect to see a huge jump in sound quality by just changing the speakers. If you are low on money, just get a head unit first. and when you make more money, then you can get the amps.