> Researchers noted that modifying a vehicle to make an illegal, disruptive noise at a distance demonstrates the callous disregard for other people's feelings that defines psychopathy.

> Because the sudden noise startles and scares pedestrians or animals, the drivers frequently score high on everyday sadism, meaning they derive personal joy from minorly distressing or startling others.

https://www.psychologytoday.com/ca/blog/human-individual-dif...

> Contrary to my hypothesis, narcissism was not a significant predictor when the other personality dimensions were included. This finding suggests that people may not, in fact, be making their vehicles louder to draw attention to themselves or to say, “Look at me!”

> The results are concerning in that they suggest that individuals who make their vehicles loud may be doing so to deliberately hurt others by disturbing them and that these individuals may be motivated by the negative state that they cause others. Although the study is a pilot study and requires replication, the results are perhaps especially concerning because some media outlets are reporting that the frequency of vehicles with loud exhaust systems has been increasing.