Ok, so I checked it just now. I got 178 degrees out of the faucet and I didn't have to do anything to mine to get it into "overdrive".
But I would definitely not turn it that high if there was the threat of other folks in the house using it, 180 degrees is f'in HOT.
The way mine was installed I can actually throw a diverting valve and they open the port directly coming out of the heater, so I think that's what I will end up doing when I kick it into overdrive. Then I have to manually throw it back to bypass to feed back into the main plumbing system so I won't accidentally leave it on 180. You might ask you plumber to ensure there is such a bypass or a shut-off to the rest of the house for the times when you use this mode?