I was hoping that maybe there was a section of the liner to cut out that would allow the subwoofer's port (which I can't positively identify) to better vent into the cabin. WeatherTech's web site states that the mat is marked where to make the cutout but I'm either too blind or dumb to find the "mark". There was more bass before installing the liner so I was hoping someone had already done this.
I have the model that is designed to fit the CX9 and it fits perfectly. I'm always loading/unloading musical equipment and it doesn't move or slide around.
Here is a link to what I bought.
http://www.weathertech.com/mazda/2014/cx-9/cargo-liner/