Car Installation

First: Install Img Tool or Alci's IMG Editor
Second: Open your IMG Manager, then find the car file and replace it with the car mod or put the car mod inside your car mod file in modloader
Third: Rebuild Archive.

Sound Installation

First: Install Alci's SAAT GUI FrontEnd and open it
Second: Replace Bank_096 and Bank_097 or put the file inside a Sound Folder using modloader.