Beef if I had the time I think I'd give the EFIE and HHO a try, because you never know. I'm not too worried about leaning out the EFIE, most engines have good knock sensors and will retard back if you go too far. I would definately go very little at a time though.
The most common thing to happen would be knocking and while this is bad under load or over a long period of time, you'll be watching for an expecting it, so it won't blow up your engine. The worst thing I could imagine happening would be the H2 exploding the whole thing before TDC and twisting a crank or breaking a con rod, but this isn't that much different than pinging so I don't think I'd worry about that too much either. Plus we'll never make enough H2 to explode that quickly. Even 2L/min is far less than 3-5% of the charge, right?
I have a car with 175K+ miles on it
it is also paid off
it gets over 45% over EPA
it has a salvaged title
tax value of it is $700
and it runs good.
I don't want to have to rebuild it or be forced to replace it. I do want to replace it but I want to have time to decide what I want and not be forced into a deal. all this and there aren't any proven results to HHO. there are proven results with the EFIE which makes you run lean (there are people that have just done that alone without the HHO).
if anyone wants to play with HHO then that is fine but know the risks and know the results of others which are hard to find. many have claimed a drop in MPG other simply disappear.....or talk about outrageous gains and then post their website selling THEIR design. you see where I am going with that one.
Be the change you wish to see in the world