Let me explain further with graphs, what happens if you do not have a remap supressing the limp modes by raising the ECM threshold, and what has to be done to still benefit from higher MAF voltages / air intake, and the associated power :
Please note that my intake is full stock. stock NISSAN air filter, stock duct to the turbo. Only mod is a wider IC to better cool the compressed air. Why not modify my inlet ? I already have too much air coming in !
At 3065 RPM ( see sensor time series display below ), I can get a 4.39V MAF voltage for only 17.2 psi, which means lots of air is flowing over the MAF sensor.
This MAF voltage is way above what the ECU is happy to see. You know what happens in those circumstances : limp mode @ fuel cut.
In this particular case, my electronic MAF & VNT controller monitors RPMs and MAF voltage. It let it go beyond the limp threshold, for a selectable time ( here 2 seconds). And then reduces the MAF voltage until we re beyond, in this case, the "less than 3000 RPM - less than 3.98V threshold ). Once above 3000 RPM, it lets the MAF goes its way, here up to 4.39V, providing the MAF voltage does not exceeds 4.18V for more than 2s ( it is the case here ).
In the meantime, the ECU provides proper fueling in accordance with the MAF value provided.
Of course, during the short period of time when the MAF is kept "under control", you will get less fuel injected, but you can hardly feel it. Diesels run with excess of air, and in this case, AFR will be a bit higher for a short duration.
Increasing the quantity of air (not the boost, do NOT be confused anymore) makes the ECM ask more fuel to the IP. And even if a good remap gets more fuel to be added for a given amount of air, getting more air sucked if you have no remap, will de facto increase the fueling. And if you do both ( starting wih improving the "air management"), you get a dual gain as if you have even more air available, remappers will be able to add even more fuel.
Last comment : you can see how "flat" my "turbo MAP" is, which displays boost vs MAF voltage, color coded in RPM.
There is no need to have a very high boost to get lots of air. I have been advocating for this for more than a year now.
Let your Patrol "breath" properly. Boost is not your friend. Highest MAF voltage is.
MAGIC BOX does it all for me now.