Yup, just wish it was as simple and well documented as on the EEC-IV Ford stuff, I've done two MAF conversions on that system and it's quite straight-forward for the most part.
MAF would be ideal, it would just "work".
If he downsized injectors he risks leaning it out at low load where fuelling requirements are lower and the maps will be closer.
probably any attempt to “fool” it is going to work over the entire rev range. It might also figure out something is up and set a code. Much safer for it to be rich than lean.
I guess a logging wideband could help determine if it’s a huge issue, but they are not cheap and then you are right back to what to do about it...
I guess I should stop throwing ideas out since I still think just leave it alone is the best plan.
Subies are kinda known for crummy fuel mileage anyway aren’t they...