I know, I know.. I spelled Bluetooth wrong in the title.
How to replace Bluetooth mic in factory location (WRX 08+)
This is a walkthrough on how to replace the factory Bluetooth with an aftermarket HU's Bluetooth mic.
The factory Bluetooth is located in the middle of the overhead light cluster.
The first step is to remove the covers of both lights. This can be done fairly easily with just your fingernail. You can see the 2 little clips holding it in. Just stick your fingernail in there and push forward to release the clips.
Next remove the 2 screws located here:
There are 3 clips holding the light cluster in. To remove the light cluster, use your nails and pull towards yourself to give the clips enough clearance to slip out.
Once out, this is what you should see (may look different depending on options installed). The little black box is the factory Bluetooth mic. Remove the 2 screws holding it in and move it aside.
Take your new Bluetooth mic and run the end of the cable through the head liner like so: (I used a flat head to guide the cable out)
Now run your cable along the liner and down to under your steering wheel and connect it to your HU. Use a credit card to guide the cable into the cracks.
By moving the factory mic over a bit, you can give yourself enough room to squeeze in your new mic. This is where it should sit:
Using some nice indoor double sided foam, stick a few pieces on your mic and put it in the empty space you created.
Put everything back together and you are done.
I did a quick test call and was told it sounds identical to the factory mic ("Like you are on speaker phone.")
Let me know if you have any questions.