Water/meth injection has been a thing for a while. Corrosion is a huge issue so thats why it hasn't been popular for daily drivers. This just sounds troublesome for the average guy to try to maintain. Snow Performance has been doing this for years
http://www.snowperformance.net/Stage-3-Boost-Cooler-Water-Methanol-Injection-Kit-p/310.htm
Yep. And Snow Performance has the shittiest components I have ever seen. I have had their fail safe module fail. So much for being fail safe. And looking at their design it is not inherently fail safe from a controls perspective. Methanol kills the pumps eventually too. Had a pump fail on me too. The other problem with 99% of the kits out there is they duty cycle the pump to control delivery, but it is very inconsistent from run to run. As well, you cannot get even distribution to each cylinder if you are just spraying it into the intake tract.
The only way I would do water/methanol injection is if it's an Aquamist kit which has injectors that you duty cycle with a constant running pump to guarantee consistent delivery. However, I would still want to plumb it into the intake manifold with individual feeds to each cylinder.
Honestly, I'd rather pay for more octane than screwing around with water/methanol injection. Race fuel is cheaper than engines when your water/methanol system fails.
One nice thing with water/methanol injection is you never have to worry about carbon build up issues that is common with so many DI engines.