[Alan Anderson]

"Pre-drilled mounting holes for the Gear Tooth sensor module on the transmission covers, and using the GTS hardware supplied in the kit of parts will make installation particularly easy."

It doesn't go next to a sprocket. It goes next to the gear with the pre-drilled mounting holes beside it. The big thick plastic washers go under the board; the small thin plastic washers go above the board. You can see that if you look closely at the picture.

Run the wires out wherever it makes sense for the way you have it mounted to your chassis, taking care not to run them in the way of gears, sprockets, chains, etc.