hihosilver, there is no vacuum port in a Diesel manifold because there is no vacuum to speak of in an engine that doesn't throttle air.
coachgeo, check with folks who use water injection on turbocharged gassers. They know how to build water injection systems with higher pressure than max boost so it does spray under boost. There might be a way to fashion a squirter like a pitot tube so it sprays with the airflow rather than across the airflow. But maybe spraying across the airflow is better for mixing.