In this day and age of varying gas qualities, inconsistent ethanol content and regulatory changes, water injection may well at least protect our engines if not add a significant level of performance.

I am seriously considering making it a part of my next build. I run 11:1 on pump gas and things are good.......most of the time. But the engine is on the edge and occasionally I need to back the timing off because of gas even though I gas up at the same place. (93 octane supposedly)

It appears that meth/water injection can produce real performance improvements in certain combos. The water injection just may be a cushion that allows for a tighter tune without being on the ragged edge of destruction. That alone would be worth the price of admission.