Nearly all car mods pass inspection. Look at what is actually checked: safety and emissions. Nothing about speed, appearance, sound, horsepower, ride height, or stock state. And moreover: if you modify a car that fails inspection, it’s on you, not the manufacturer!
You are correct in the larger sense, I am just pointing out details. Sound checks are part of checks in some places where there are sound limits on vehicles. Some "mufflers" are more like megaphones.
