[Richard L]

I took sometime to digest the information.

I can see that you have a few options to incorporate WI with certain degree of safety.

Option1:
System2c with a DDS2/3 flow sensor - as soon as water flow is detect, you should be able to use the output to switch a relay to enable the HOM switch (y ou may need to find out which wire from the HOM unit tell the ECU to switch MAP)

Option2:
System2c with a DDS3 flow sensor - as soon as water flow is detect, you should be able to use the output to switch a relay to connect the factory boost solenoid to work. If water is not redected within a set time by the DDS3 undwer boost conditions, the wastegate will remind at default boost.

Option3:
Upgrade the 2c to 2d and use the "fault output" to de/select the above options when "water fault" is detected.

If you pick a preferred option, I will make a wiring diagram for you.