If you were to change the color of you're vehicle, by either Spray paint or Automotive paint, would you have to go the DMV to have them update the registration?

You are supposed to mention it when you register it. So the answer is no. You don't have to. The only time you technically "should" is when you renew the registration. This helps if/when it gets stolen.

Ok.
So if a I get pulled over by a cop and he see's the vehicle color is different then the registration, he can't get me for anything?

No

i never did

been pulled over, never had an issue