[rotrex]

Just had a look at your drag video. For water injection, the AFR was in the 11.2-11.5 range. That is a tad too rich for heavy water meth injection in my experience. Flame speed drops a fair bit that rich. I'd try to not run richer than 11.8.
With 30PSI you should see insane HP numbers. :-)

The more complex and "bended" the intake manifold is, the worst central injection systems become or the more advantageous direct port with well positioned jets gets.
BMW uses 2 jets for their M3GTS with water injection, but have positioned them well in the plenum chamber for good distribution across the 6 runners. They also only spray small amounts and with it add litte extra power.