In an ICE car the part of the tailpipe which is wider (which I believe is also were the catalytic converter is) is tuned to change the engine noise (mostly to reduce it, but it can also be tuned to make it “purr” rather than “roar”, like in sports cars)

Cut that out and the car becomes much louder (and if it’s not diesel, I believe it’s with the kind engine sound one associates with muscle cars).