interesting stuff.. about pouring water down the intake its not bad.. ive done it several times.. its great for cleaning out carbon if you pour it into a hot engine and kill it so it on the valves, in the combustion chamber etc and let it sit for a while and the steam will do its trick.. but i recommend using GM "top engine cleaner" first or you may run into problems with larger chunks of carbon sticking to valve seats i.e. compression loss, no start, etc.. never happened to me but ive heard stories of engine tear downs due to such a thing.
mike