Lots with that hull use the XPTH 9 HDSI 180 T thru-hull transducer under the transom extension and use the XP 9 20 transducer for shoot-thru 2D sonar. Those two transducers are connected to the display with the AS SIDB Y cable.
Even if you use the transom SI transducer on the transom, you should use the shoot-thru. That applies to all high performance fiberglass hulls.
There are some installation pictures posted on the Bass Boat Central forums in the Humminbird Installations and Networking Information Resource topic.