Not compressing is a good thing
OK we are talking minute amounts here it's not a hose pipe running into the inlet it is a mist sprayed into the inlet air stream, this cools the air. The air is very hot from the SC and even with an IC still hot enough to cause det if, like me, you are stupid enough to run high comp pistons and after market cams.
The water turns to steam in the cylinder and should not cause any damage the "not compressing" has been referred to as the steam engine effect - in the good old days they ran engines on steam and it can (as it becomes superheated steam by the fuel burn) increase down force on the piston and therefore torque - the reality is if it does you probably wouldn't read the figures on a dyno its not enough in there.
But again we go back to its cooling properties - that's what I use it for and it works 2 tuners on 2 dyno machines can detect knock without the water so I'm keeping it