OP, which Nismo version diff are you getting? The OEM Nismo diff really isn't an upgrade as has already been mentioned.
High capacity will help with cooling. Are you tracking the car? Probably don't need it otherwise.
Diff brace doesn't fit with certain exhausts (like Fast Intentions style canisters) so be careful. Good upgrade for drivetrain stiffness (we all like that
) if that's what you need.