I firmly believe that it should be illegal to make your car louder
When you're in another car, it's already bad enough. But picture this you're just a pedestrian minding your own business, and all of a sudden, a car goes by making that obnoxiously loud gunshot sound as it accelerates. Now, imagine that same scenario in a downtown area, where all the noises are amplified as they echo off buildings left and right. The result? It's absolutely detrimental to everyone's ears!
This issue is similar to people who blast their music in public spaces that we all have to use. It's plain rude and annoying. Noise pollution is a real thing, and there's no reason for cars to be contributing in such a flagrant way.
I know that some car enthusiasts like to tweak their exhaust systems, but there has to be a limit. Can't we all agree that excessively loud and unnecessary car noises should be frowned upon and, ideally, outlawed? Let's share our public spaces with respect and consideration for others.

In some places, depending on the modifications, it actually is.
Where I live its illegal to do any modifications to affect the bypassing of a muffler to the car to make it louder ((or just in general))