Yes, turbo GN guys have been using water/methanol injection for years. This product will not actually give you more horsepower. It allows you to run more timing and/or boost safely so in the end you can make more horsepower.
I am not the most experienced with s/c but, Water/Meth injection has been around since WWII. They used it on the P38 The only draw back is that they tend to corrode(sp) everything.