Ah... so the bubbler introduces outside air as well as water?
Water/meth injection can either use a water/meth mix or run on pure water. With pure water, you still get power and detonation-suppression benefits, even without the extra octane boost of methanol. I guess when you say "injection", you're referring to the cheaper kits with lower pressure injectors and nozzles... (like the cheapo kit I have...
).