I finished building the manifold and am ready (when a minute is free) to mount the manifold in my attic. It is a 15" x 15" x 8" box, with a smaller vent extending down from the box and through the drywall (about the size of a heating register). For visual purposes in the main room, I have to mount the mainfold sistered to a joist, and cannot mount the manifold across two joists. So far, I have some L brackets to mount to the box and to the 1/2" plywood floor. Home Depot is too far away to get some of those Strongties. Anyone have a better idea, as I don't want all the junk to rattle along with the sub.