I have revised the drawing to conform to your latest addition (priming pump).
We still need to clearify how the "water fault" signal is interfaced with your current set up.
I gather from various posts from other SRT owners that the HOM line is not accessable. So uit leads me to consider other action such as lowering the boost. It can be done with the DDS3's pin #11 and #12 to cut the wire that goes to SRT's bleed valve. I need your help on that. Perhap some one can post me a picture and let me know the wiring colour that energise the valve from the ECU.
Alternatively, we can leave that part alone and let the knock sensor to switch off the HOM mode upon presence of knock. What you you think? I will update the drawing further.