Yes, the ECU would adapt and negate the enrichment, up to the system's inherent adaptation limits. It would do the same with fuel pressure hacks, or anything else where the ECU sees the mix at the 02 sensor as being anything other than stoichiometric. (obviously speaking of closed-loop mode here.) WOT enrichment is one thing, but "on the fly" tweaking during closed-loop operation has some inherent advantages, as Duxthe1 has discovered.

Those are the reasons why I'm so interested in Duxthe1's methodology. Same questions apply:
1.) are you planning to produce this?
2.) would you like to expand into a wider potential market?

I know that there would be PLENTY of interest from certain groups of enthusiasts that have LH cars!

__________________
Current rolling stock:
2001 E55 183,000+ Newest member of the fleet.
2002 E320 83,000 - The "cream-puff"!
1992 500E 217,000+
1995 E300D 412,000+
1998 E300D 155,000+
2001 E320 227,000+
2001 E320 Wagon, 177,000+

Prior MBZ’s:
1952 220 Cab A
1966 300SE
1971 280SE
1973 350SLC (euro)
1980 450SLC
1980 450SLC (#2)
1978 450SLC 5.0
1984 300D ~243,000 & fondly remembered
1993 500E - sorely missed.
1975 VW Scirocco w/ slightly de-tuned Super-Vee engine - Sold after 30+ years.