Installed this Bluetooth receiver the other day. Very happy with how unobtrusive it fits with the stock stereo system. Was able to hide the majority of the wires behind the dash without having to cut anything.

Here's how I did it if you're curious....
Test to make sure your Bluetooth receiver works properly then....
STEP 1: Turn off your car and remove trim pieces, stereo and loosen climate control/storage boxes. (Unplug the stereo completely and set it aside, everything else you can just leave sort of loose)
STEP 2: Starting with the power supply, plug that into the 12v socket. Run that wire (BLUE LINE IN PHOTO) and the rest of the device to the passenger side. With one hand slip it underneath the passenger side dash. With the other hand fish it out through the top where the stereo was.
STEP 3: Put the AUX cord (RED IN THE PHOTO) near the AUX input side, keep it horizontal or slightly above the AUX INPUT to help avoid pinching the wire
STEP 4: Put the receiver towards the top corner of the trim, here you will see a nice groove where the wire (GREEN IN THE PHOTO) fits right between the trim and the stereo.
STEP 5: Carefully put everything back together being conscious of not over pinching the wires. When you place the trim pieces on, start at points away from the wire then slowly make your way towards the wire. It will bulge out the trim about a 2mm around the wire, but itís hardly noticeable from driving perspective.
STEP 6: Once fitments how you like, adhere the receiver to where you want it and then, go back underneath the dash from the passenger side and tape the junction of wires to the inside of the dash to prevent them from moving around.