water injection for turbo usually use the pressurize air (boost) from turbo to "push" water from sealed water container (with controlled vent) to inlet pipe after air filter or turbo.
appropriate nozzle to make small mist of water droplets required to make sure it "blend" with intake air.
water injection benefit from colder air intake temperature and thus some power increment can be felt.
Boost goes up nicely to 0.5 bar at 3000rpm but then starts to drop to 0.3 bar starting 3000rpm until 4500rpm. After that it fluctuates about between 0.4 and 0.3 bar until 6000rpm. Any idea why? Boost leak?