I have an 2013 G37 sedan with Z1 intakes, motordyne art test pipes and motordyne cbe with the Osiris standard tune.

I want to install the Z1 ported upper manifold but don't have the money for it and a retune right away. Will it throw off my air fuel ratios to a dangerous point until I can get a retune, or will I be safe for a few months?

 

I had almost the same setup without the Osiris standard tune and I run the car without tune for at least couple months during the winter. I did not have any problem so far during that period or after my tune period.

 

I think the Osiris standard uses closed loop fueling and so it will probably handle the new manifold without a problem. Just drive it and the fuel trims will adjust.