First off, what is your water/methenal ratio? I run 25% methenal, 75% water. I'd advise against running straight water. Also, what are you looking to get out of it? Hot Rod added horse power, imporved MFG or cooler pulling temps? How much to inject, nozzel size and pump pressure depends on your mods. if you're running high HP (400 hp & up) then big nozzels and high pump pressure. If she bucks Your injecting way too much. Turn it down till she runs smooth. Be carefull or you might pop a head gasket. Who's kit are you using???