Maximum1, I'm going to concentrate on the mod you presented. It looks to me to be a sheetrock screw installed into a mainspring to compress the mainspring. Correct me if I'm wrong.
I modify/build my guns, and I carry the guns I build/modify. I build/modify them to gain a more accurate, reliable and safe weapon. Each modification is geared towards these ends, although some are more specific than others. Because one of these weapons may someday be held up in front of a jury of my "peers", I want the modifications to be defensible in court. I want them to be professional looking, and to be accepted as safe among my peers. I do not think a sheetrock screw in a firearm meets that criteria. Thus, I would be opposed to the modification you have presented.
When I was younger, I was a much more tactical kind of guy. As I grew older, the black tactical stuff on my home defense shotguns was sold off and replaced with wood. I did retain the sidesaddles on them, however. My carry guns became more stock, or at least more pedestrian appearing. Black tacticality was traded in for old slabsides and revolvers. Recently, I purchased a SW1911PD for carry, and the only mods I plan to make are black rubber grips, and a Wilson magazine. I will polish the lockwork and feedramp with rounds downrange instead of with stones.
It is true that no court case can be cited where modifications directly resulted in a conviction from an otherwise justifiable shooting. Still, having been in a couple of courtrooms, (medical malpractice) I know that jurors are influenced by many things other than the facts. They are influenced by emotions, gut feelings, and how things look. These jurors may hold your future in their hands. There is a fair chance that they will be gun ignorant. All it takes is one "expert" on the stand who takes issue with your sheetrock screw, and suddenly that jury may stop seeing you as the model citizen who was forced to defend your life. They will never cite that as a reason, but the influence is there. It shouldn't be that way, but it is. The political climate and the gun climate of the area you live in will have a lot to do with how far a jury is swayed, but even in the best arena, modifications that are not widely accepted can make you look negligent or reckless. In a civil or even a criminal case, that could cost you dearly.
Just my two pesos.