This is a water injection setup with a high-pressure headlight-washer pump and an unknown injector. (The injector is a Bosch Cold Start Valve Bosch # 0280170043)
It's controlled by throttle position (when the system is switched on).
Never had to use yet (not so hot weather), but previous owner used to mix alcohol to water one-to-one when it's hot.
This is the injector:
