Careful! I have heard that a lot of the new cars' electronics are actually funneled through the radio and removing the unit could wreak havoc on the rest of the car. In other words, it is no longer an independent unit from th rest of the dash componentry. This is also the case with my Audi.
I believe you can replace the amplifier and speakers, while leaving the radio unit (amp is downstream from it). The radio unit is noiser than other heads, but it's so integrated with car electronics that you would regret swapping it.