If I wanted to color match the Nismo kit and or spoiler, how does one get the paint matched to stock paint?

Will Nissan do it?

 

The paint code would be listed on the door panel. Any body shop should be able to order the paint and paint the part for you. As long as the car is brand new, there shouldn't be any matching need at all, since the paint on the car hasn't faded at all yet.