Pete,
Sorry but have been really busy at work and home and just now getting to answer e-mail and board postings…
The y-cable you are talking about is the AS-Si-DB-Y cable. I call it a transducer splitter cable because it splits the Si and 2D sonar connections. It allows the Si transducer to keep using the Si sonar (and water temp) but allows the 2D signal to go to a second transducer. Many install the second 2D only transducer inside the hull. The restriction is that it is a DualBeam only transducer as it will not support the connections to a QuadraBeam type transducer. Since this is a cable and not a switch; there is no automatic switching between transducers. The 2D sonar will always come from the second transducer.
I have not heard one way or the other if there will be any software updates coming out for the Matrix 97 units. So I don’t know if they will get the SwitchFire update or not.
The extra temp cable (TG-W) is an auxiliary temperature and can be added to any of the Matrix or other units that have at least the 3.850 software version or higher. If your Matrix 97 is running the current 4.210 update than it has this capability. All you have to do is buy the temperature sensor, mount it (some use this to monitor live well temp) and access the added readout capability and menus that your unit will start displaying. You should have the ability to select the Aux. Temp as a digital readout in addition to or in place of the transducer’s temperature readout. There is also a separate Aux Temp Alarm menu. Now if you do not have a transducer that has a built-in temperature sensor than the auxiliary temperature sensor will be displayed as the normal temperature sensor.