I see... but I am talking about this one I ordered couple of days back:
http://www.ebay.com/itm/2012-MODEL-T...item3a6b88143e
It has thermal switch in it which activates device after certain temperature. I agree with the theory Darol Mason explains, however I need to see it in works. I just ordered his HHO kit also, as I am loosing faith in 772 kit I purchased from hhokitsdirect.com, their support is also one of the reasons I want to now stay away from it. The new kit is fairly small and simple, I will be able to install it pretty close to air intake where as for 772, I had to install it in trunk! Its too big to fit in my Corolla 2000.
FYI the link to the kit I purchased is: http://www.ebay.com/itm/Most-Efficie...item3a66bb7798