You are still thinking like the MAF delete makes it run in open loop - it does not. It still runs in closed loop like before, so if there is more air it will give you more fuel. This is a factory mode that was run stock on many thousands of cars sold all over Europe.
All of the fueling is closed loop / target based on the N52 - so unless there's a different lambda target you want at full load, there's no reason to re-tune anything. When I first did the MAF delete I wasn't even sure it was working because it sounded exactly the same at startup (no weird idle, hunting, etc).
As far as the SC, interestingly I think it's definitely possible to make the MAF work with the SC - but ESS couldn't. I'd guess it's the same reason their MS45.1 supercharger tune was completely broken. But on the other hand, it's not really necessary - it was *designed* to not need a MAF, and IMO it's one less failure point. Keeping in mind ESS borrowed my idea for the euro based tune when their old "cut the MAF wire and run it in limp mode" trick wasn't working so well..
