This forum has stickied threads on this very subject by experts such as Massad Ayoob. The takeaway is this: Imagine you are brought up in front of a jury made up of people who know nothing about guns, by an anti-gun prosecutor intent on nailing your hide to the wall. The DA is going to hire an expert who will examine your gun in depth and present his findings in court. Now ask yourself this: Is anyone going to care that you installed night sights on your gun? Night sights are probably a factory option on your pistol. It's also a common convenience modification that does not change the lethality or safety of the firearm. It doesn't present you as reckless or bloodthirsty to a jury.
I want you to understand that ND's really are prosecuted in this country, even when no one is hurt. The magazine safety might not even be a factor in the ND but the modification could still be used to paint you as irresponsible or reckless to a jury. No one is going to care about your wood stocks or night sights.