i have a snow performance water/meth injection setup on my hatch. it was a fairly painful install, hopefully it proves worthy of the time and effort involved.
you can run windshield washer fluid too i believe, it contains some methanol. probably not a 50/50 mix. you do NOT want to go much higher than a 50/50 mix, as the meth can begin to corrode the aluminum parts in your engine (from the snow performance manual)