From what I've read on the forums, the 4080 12" enclosure will fit in a G35x as long as the foam spacer next to the spare is removed. However, wouldn't the trunk carpet mat itself still get in the way of the enclosure sitting flat on the floor? Since the other foam spacers are there, the mat be at a different height in other areas of the trunk. I'm finding it difficult to describe exactly what I mean but I would love to see a picture of a 12" box in a G35x trunk.

 

The X trunk is the same as the RWD trunk with the full size spare. It will fit fine with the spacer removed. The carpet/mat helps it pressure fit into place for a perfect fit.

 

Don't worry about the carpet. My 4080 box is resting on the carpet.