[EdKiefer]

I have had some improvements with water injection on various vehicles .
On my 1974 Opel Manta that i turboed I used 2 systems one using boost pressure in a sealed tank to spray into the intake, right into the compressor wheel .same car I also had windshield wiper pump triggered off boost switch . The seal tank was better as the amount of water flow varied according to boost . this allowed a few more lb of boost on pump gas .Used to run around 12lb on 8.0 CR pistons .

The other vehicles used a varible speed module that would vary motor speed according to rpm and load. the spay was pointed right down into butterfly of carb (was a V6 2.8L GM -1980 era ). This alowed me to raise ignition timing to just slight ping with no water and with all fine .

Only downside is the jets over time need maintenance as they can get clogged .both vehicles were carbed . I have tried it on fuel injected engines with not as good gains , which I think is because of longer runners of fuel injected engines and how there routed .

You don't want water injected on light loads, you want it in general on mid to high loads, so entering a vacuum hose is bad IMO . You need it to spray with atomized spray pattern .