The Coocase base has a grid pattern that uses square washers and bolts/clamps to hold the base onto the rack. With the u-bolts, there were only a few options in the grid pattern to hold them onto the cross bars of the Faco rear rack. See the pictures below. I also had to grind down a few of the supplied washers to fit along the top edge of the bases' triangular grid.
It's on very tight, but I may use a few of the supplied bolts and clamps on the top edge for extra holding power just in case. The electrical portion of the install was amazingly easy. Using the supplied wiring kit and a few additional lengths of wire (not supplied) the wiring took about an hour, mainly because I'm very slow, meticulous and not very experience with electrical work.
There are two ways to install the wiring according to the instructions. One for CANbus and one for non-CANbus systems. My GTS (thank you Midnight Rider for clearing this up) is non-CANbus, so I needed to use a supplied additional harness. I ran the base wiring through the vents near the gas cap area down into the engine compartment. Then using the supplied connectors, I ran the hot and ground wires from the battery compartment (not connecting to the battery yet) to the engine compartment. Then I opened the taillight and using the supplied connectors, attached the supplied harness to the brake light hot wire and the license plate light hot wire. Then ran a wire through the rubber grommet behind the taillight into the engine compartment.
I hooked all the wiring together according to the instructions, and then hooked up the hot and ground wire to the battery. I turned on the lights, tried the brake lights, turn signals, remote and all worked great. Satisfying project completed and I can finally store my helmet on my scooter.
Base installed with center cover.
Base uncovered showing u-bolt pattern.
Underside of base and rack.
Side view installed.
Not room for much else with my Schuberth C-3 inside.