Thanks guys, IŽll keep you posted.
So far the thing I seem to have confirmed (I had my suspicions) is that the hypermileage abilities of the D15Z6 (and likely D15Z1) likely comes from the engine itself. Running it super lean is just sugar on top, really... judging from my MPG running stoich.
Seemingly the combustion chamber is stupidly efficient. For example, when adjusting fuel tables you can hardly feel the difference between AFR12 and AFR22.
A side effect of all this is that weŽll probably be tuning a couple of unmodified EK3Žs also. During the 2-3 weeks I have been using my own program to tune part throttle, I find the car more or less transformed and not "quirky" to drive any more.
Anyway, IŽll happily share fuel/ignition tables if anyone wants them. Still not sure on how much timing to run @ super lean, though. Any tips on how to reliably read actual ignition timing during part-throttle on an unmodified car are quite welcome
/Allan