I put this on the Seafoam thread then saw this which it directly applies to-

I would throw in this disclaimer concerning the water - Use caution with the water (amount misted in), esp in high compression engines. The Sports Car Club of America used to allow water injection in some classes (water does not compress, thus a major compression bumper). They outlawed it b/c it grew tiresome stopping races to pick up engine pieces as racers do tend to get carried away.

Matt