found a quote on the Water Injection board that might peak your interest
here is link to the thread
http://waterinjection.info/phpBB2/viewtopic.php?t=63

(Iknow, I know this quote deals with a different car but the underlining fact should hold true.)

Bruce

I'm getting the WI just for a better afr, yeah right.

 

Ran Auqumist's W/I system on my last car with rather amazing results...

seeing as i live in Cali we get the 91 pisstane i was having some major problems running 20 Psi on a 9.5-1 comp motor

after installing the W/I i noticed a few things......

lowered detonation/knock count considerably... esp @ high boost

ECU was able to dial in more timing because of the reduced knock (timing = power)

Intake air temps were down almost 40 Deg F compared to when the W/I was off @ similar boost levels

Steam cleaned the carbon out of the Combustion Chamber (instead of a black soot, i could see the concentric rings from machining/casting in the piston head)