something twigged in my mind about this so if you're Aussie and have a car that will go into lean cruise and you want to stop adding to atmospheric damage (NOx makes acid rain, IIRC), go and look into
cooling the burn
the second site advocates an active injection system, but the passive bubbler I have on mine (uses manifold vac) to bring a little bit of water into my manifold makes a bigger difference than I expected. of course, I had to adjust what the computer was seeing at the MAP sensor (a small vacuum leak, which makes it open the fuel injectors) with a MAP Adjuster to make it really worthwhile...and strike a happy balance with the o2 sensors using an EFIE from that 2nd website.
It's really up to you how far you want to take this - and as the first website says, be careful and don't blame us around here if you break something expensive - but it seems you'll need to dig into hacking the computer with software to get the lean burn happening, and then cheaters to make everything from the sensors to the hacked computer make sense on top of your groove.
I'd bet that the folks with California emissions systems in the states might benefit from looking with a sharper eye at this...