Louder and more distinct audio for upgraded engines

We want to be able to actually hear a fully customized car when idle. A V6 or a V8 or any other engine fully built should sound raw and mean racing through the city streets and highway of Tokyo I mean how cool would that be. Anti lag on a Supra for example would sound like a mean AK-47 firing. Its little details like this that make this game so much fun then it already looks.