I had the first one you posted a link to...

Basically if you spray meth into the throttle body it goes throught he s/c into the intercooler and through the manifolds, essentially cooling the intake air that the supercharger is forcing through...now as for the octane boost most assume they get from the meth I dont think it happens, by the time it goes through the s/c, through the core of the intercooler theres not much left.

I think the objective of the water/meth is to cool down the intake air going to the manifolds, now what has me confused is this.

People that have sprayed into the Y Pipe seem to get no gains, but yet logically it's the best place to spray because it bypasses the s/c and the intercooler and goes straight into the manifolds, one would assume that would give the engine the coolest air, but yet people that spray through the supercharger seem to get better results, it doesnt make sense to me by the time the cold charge from water/meth gets to the manifolds its no where near as cool as it if you were to spray into the Y Pipe...hrmmm