If it was put on your car at the factory and has a

[Keith Seymore]

More relative to the topic at hand:

I have followed literally tens of thousands of GM vehicles down the line as part of my job responsibilities, and another dozen or so for my own purchase.

Any deviation from a production build is tricky, even with a full staff of attentive personnel who are being paid to manage it. Adding individual unrelated pieces of stand alone content (like a stray trailer hitch, or upgraded engine back in the day) is not too bad but as the interactions go up, like with added related electrical content or controls, the complexity skyrockets.

I can say with authority that assembly plants do not look kindly on engineers who shut the line down due to some unintended consequence of a change (whether real or imagined).

K