I just downloaded AC, and I've been playing racing games since GPL came out. The real Z4 GT3 car is IMO the best sounding current GT racer, and I was disappointed with the default engine note in the game. I downloaded this, and I have to tell you... watching a replay of a hotlap and hearing this engine note gave me goosebumps. It's absolutely fantastic work. As close to the real thing as you are going to get in a game.