I have a thread a few years back. You can leave your stock radio and have all the functionality of modern radio!!!

You purchase a Bluetooth amplifier about $100-200 depending on desired wattage. Simply hook your desired speakers right into the amp. I mounted mine underneath the rear package shelf.

Getting a bit deeper... you can use the functionality of your cell phone or iPod to control your radio. You simply pair your phone to the amp and it will play what your phone /iPod plays, when a call comes in you just talk through your phones speaker and the audio output is through the cars speakers.

Again I stress system modifies nothing from your original equipment!!! You only need have your phone in the car. Simply hook your speakers directly to the amp and away you go.

Another key feature is that the amp has a voltage trigger. The system will not turn on until it sees 13v and turns off when votage drops below. This ensures that there is no voltage drop when parked or KOEO.