Can only adapt so far. Remember when Nissan designed the engine, it wasnt designed to be modded, so they only have a certain window of correction. Take it too far and it cant add more fuel for the air you give it, then it runs lean.
The OP will likely be ok, I think its mainly when you add in headers to the above combo of beathing mods that it gets dangerously lean.
EDIT: It was Octets car that I remember the comment from:
Subject: Car booked for UpRev @ Abbey tomorrow morning
I still think that although its worth getting done, its still not worth doing before you have completed all the mods you want to get.
My AFRs were pretty much as they should be even after headers were fitted