Aquamist HFS-3 and MINI Tank GB

[BostonR56S]

There isn't a great amount of room to route things through there. It can be done, but I cut the sht out of my hands wiring my head unit up there when I used to have it up there. A good place to out it is behind the padding under the carpet on the footwell back wall, look up to the top of the carpeting, about where your toes would be if sitting in the passenger seat with your feet pointed up.
I have my iPod control module there, and my laser jammer computer.