Front speaker that fit without mods

Originally Posted by Guard Dad

Hi everyone!

Just picked up my new 2010 coupe w/sport package last night. No touring package so I have only the basic audio package and am looking for affordable improvements, probably just a speaker upgrade and some sort of iphone/ipod interface.
To my ear the factory system is short of bass, boomy in the mid bass and lacks brilliance in the mid and high ranges.
In checking out this thread it would seem that the polk db6501 speakers are popular. Are they a good choice? Saw some photos of the door without the trim, would 6x9's be a better choice?
My factory system has no rear speakers yet seems to have a functional fader, does it actually have an amplified output for rear speakers or is it a pre amp in need of an accessory amplifier?
Is the only way to connect an ipod/phone via the faceplate mounted aux jack? I'm not concerned about phone functions just audio.