Do water meth systems do much when you are under say 2000 or 2100 rpm or are they mostly up in the higher rpm band? Guess I am looking from a fuel savings perspective.

 

The snow stage three designed their system to do exactly what you are asking. And it is based more on boost levels than rpms-- you set the boost levels to come on at too.

 

I have tried it to save fuel and it does not work (for me anyway)
They spit and sputter some if you spray any decent amount of water below 13 PSI boost. If you are running at 13 PSI you are accelerating and not going to worry too much about fuel economy unless you are towing.

When towing I have noticed I had to let off the fuel a little to stop from accelerating once the water starts spraying 100% (30% meth)

 

Kinda what I was wondering is if it was primarily under accelerationor high boos for climbing hills. If so, not really going ot help for cruising mpg.

 

I have been running water/meth for a long time now and I have seen absolutely zero fuel savings. It is a tool to help keep EGT's down and for a slight increse in power.