If i put headers on my d16y8 eninge, could it f*** up the O2 fuel and oil mixture?

 

Fuel and oil mixtures? Do you mean fuel and air? If thats what you mean, your engine's computer will automatically recalibrate itself for the correct ratio.

 

i mean fuel and air mixture

 

the answer is yes and no... yes, it will slightly alter your air/fuel mix. BUT the change is minimal enough for your cars computer to compensate the change. So the end answer is: get the header and dont worry about your a/f ratio.