In my sedan it is behind the glove box. I believe the coupe is the same.
There are a few 10mm nuts holding it in place if you want to remove it.

The technosquare site has more info.

 

Several bolts to remove to get behind the glove-box. The In-cabin filter's back there as well.

It took me about 50 minutes the first time to get everything off and back on, but I just changed to a new HEPA filter last week, and it only took me about 20 minutes or so this time around.

 

Yes on both G's, the ECU can be accessed from behind the G/Box.
C.

 

To get to it you need to pull the passenger kick panel.
Then there are 6 screws to drop the glove box.
To remove the ECU there are 2 10mm nuts.