I'd like to see a system with a decent amount of punch. My experience from stock factory systems are that they are great quality, but just underpowered. I have an Infinity Stereo system from the factory in my '04 Tiburon, and although it sounds pretty nice compared to other factory systems, it's still only powered with around 350 watts, and a single 10'' subwoofer.
I'm not looking to extend the Sky's Monsoon system too high, i'm just looking for something with moderate punch. I'd like to see instead of a single 8'' woofer (stock) perhaps either single or dual 10'' subwoofers, with about 500-600 watts powering them. Nothing too excessive.
It'd be nice for them to be installed in the rear wall of the car behind the seats, rather than taking up room in the trunk, since it's very limited to begin with.
As far as head units go.....I'm not looking for an advanced touch screen, or dvd abilities.....but more of the mid level things, XM ready, MP3, ipod ability, etc.