RSX Audio Help!

Hey guys, my girl just got an Acura RSX and the sound quality isnt that great, I dont know the car that well, but I just finished up my audio system on my Supra and it sounds great, but its a little out of her leauge...were just looking for something with a good sound quality and decent bass, nothing to crazy, but nothing to cheap..anyone have any ideas of a good setup? I was thinking just change the door speakers, and put one small sub in the trunk, or maybe two? what would be better? and could we still work off the stock amp or would we need an amp also? And should I still use the stock headunit? This isnt the type S with the bose system, just the regular Acura system...and does anyone know the door speaker sizes?? And what can fit in there?
Any help would be greatly appreciated.
Thanks!

Ok what do you think of this...
Infinity perfect 6.5" component speakers in the front, with the tweaters mounted on the dash,then I would have to find some rear speakers then the infnity sub with the selfpowered amp and a new headuniti that will power the door speakers?..Think that would work? and sound good?

How about a decent $200 head unit, with 70 watt speakers in the back and 50 watt speakers in the front(you'll probably need an amp for these). I personaly don't think you need a subwoofer if you have good speakers. Check out www.sounddomain.com, they tell you what you'll need to make something fit in your car.