I thought I might do an update on this regarding reliability. I've been happily daily driving for the last 5 & 1/2 years on a 500rwhp tune running the aquamist system. I've only touched the system once to upgrade the spray injectors to a larger size and to solder part of the circuit board to increase the flow. The latter was done by an electronics shop in accordance with the aquamist manual. It was quick and easy, the shop didn't even charge me but I wouldn't recommend doing it yourself as the solder point is 1-2mm with no room for error.
To date, I've had one of the plastic push line fittings fail a few years ago (a 1 minute $5 job) and today the gauge sh*t itself after a few weeks of slowly losing LED lights off it. It's $250 to buy a replacement gauge. I still must say that I'm still very happy with the systems reliability. I'm not sure why the gauge failed. My car is rarely parked in the sun but when it is it's fricken hot in Darwin! Like you get back to the car and the entire centre roof light fitting has dislodged and is hanging down by its wires because of the heat. When the new gauge arrives, I might relocate it off the windscreen.