Thanks for all the information guys.
I've been looking for this product locally, with no success up to now. I think my engine will be making more heat with the supercharger, and every little helps.
I must read the Redline technical sheet thoroughly. So far as I understand this type of product is called a non-ionic surfactant, which agrees with Phil's definition.
Changing [reducing] the surface tension of the water should allow the liquid to shear from the surface of the cooling passages. Normally, the pumped coolant fluid will tend to replace the liquid in the centre of the passages more than that which touches the metal. Surface tension causes some of the fluid to "cling" to the metal [or hose] surface. This clinging liquid will be getting heated more [or cooled less, if you want to look at it that way
], and will not get physically transported to the radiator for heat exchange purposes. This in turn can cause this localised boiling effect.
I reckon this product is a Good Thing, and I'm getting some for my motor.
BTW, obversely, it will also help your coolant to heat up faster on cold days, because the benefit it gives is one of better heat transfer. It should mean your heater will be warmer quicker in the winter.
Joe