Is any body running an E30 mixture of E85 Ethanol on stock fuel system?

[Volfy]

Since water doesn’t compress, wouldn’t you also get a very slight bump in your compression ratio Using water?

That's if you squirt in enough volume of water for that effect to be significant. That would also ONLY be true if said water stays in liquid form.

The main purpose of water injection is to take advantage of its high latent heat of evaporation, in order to lower the otherwise quite hot temp in the combustion chamber.

So a good system would atomize the liquid as fine as possible so most - if not all - of it turns into gaseous state, which is compressible.