Do you have more specifics on the failure? What the system was, how it failed, what failsafe was used.

Between knock sensors and the various fault detection schemes, how is this different than other device or sensor failures, for example a flex fuel sensor?

This is a blog about water/meth on a Civic "R" DI using a Motec 142: motec – VitTuned Blog AEM also had video showing a simulated water/meth failure on a engine running on a dyno.

Bingo.

Eh that's post compression though putting the nozzle in the volute like that, Idk if you would see a density increase as much as before the compressor wheel... but I do not have experience with nozzles there.

I wouldn't be drilling into the side of my housing ether.

ive seen it with all the mainstream failsafes, cmgs, aem, DO, snow etc. PWM controlled doesnt react fast enough. Especially when its multiple lines being run, or a line comes loose/splits after the failsafe and failsafe still sees flow, just not getting into the engine.

flexfuel sensors measure content and connect to the ecu/standalone directly to adjust based on "octane", not volume.