I finished my subwoofer enclosure and installation tonight! It turned out so well, exactly as I planned it

It fits exactly behind the lip on top of the storage box, and the bolt that I put through the firewall was lined up perfectly with the hole in the enclosure. I also tried sitting in the passenger seat and I was pleased to find that the seat can be reclined perfectly (to my liking at least) without touching the enclosure (I'm 6ft tall).
Here is the finished product:





This shows the sound deadening on the inside (from Jaycar):

This is how it started: