I'm thinking of doing the same thing. How difficult was the install on the basslink? I've been looking for a place to put something back there, but I don't want to cover up all those compartments.
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Basslink allows both speaker-level input and RCA input as signal source. Moreover, it has auto mode that will turn itself on and off, eliminating the need for turn-on lead. The only connection involved is speaker-level wire which can be taken from rear speakers, and the power cable directly from the battery with an in-line fuse close to the battery, and ground the wire anywhere to the body frame of the car.
One of the way to avoid covering up the 3 compartments in the trunk is to mount the sub onto the back of the seat. The installation should be relatively simple, though maybe time consuming running and hiding the wires. :)