To add some variation, the car comes with a silenced exhaust version. 

Simply, run the Exhaust Type.bat file from the /sfx folder to keep swapping.

A pop-up message will tell you if you have the Standard or the Silenced version installed.

In Windows, you may get a warning message, but this is an Operating System precaution. 
The code is by RSS and is only intended to make swapping sound banks easier. 