So, my kit came today. The fiberglass box had minor shipping damage.. but nothing a proper amount of Loctite couldn't fix.
Before I even started with the install, i cut out the little Trunk window. Curious if that makes one or two extra dB.
Now to the Jack Nut. Throw it away immediately! This thing died after one or two firm turns with the bolt. I had to improvise and did it that way: Just put the bolt through and managed to get two nuts glued to my fingers(!) through that bigger hole aside and onto the bolt. That was enough of messing around for one day though.