Active Yaw Control is the system Mitsubishi use on the Evo 4-10 as part of the rear axle. The AYC system uses a clutch pack to send different amounts of torque independently to each rear wheel, depending on a variety of input sensors including G sensors, ABS. These sensors feed the AYC ECU information on the attitude of the car, how much slip is being generated, e.g. if the car is starting to oversteer or understeer, the car will vary the torque sent to each wheel to correct the yaw moment of the car. This aids cornering allowing you to corner faster and harder. Of course the AYC only operates under acceleration and is not a foolproof system. An Evo can still oversteer – especially in the wet on poor tyres. AYC does not defy the laws of physics. Personally I like the feeling of the AYC system. You can sense the car shuffling power between the wheels as you accelerate out of a corner. As you start to expect the rear to slide and anticipate adding a fraction of opposite lock, the AYC system sends the power to the inside wheel and the car simply grips and goes. It’s a very strange sensation when the AYC is at work; You are expecting to have to add corrective steering lock if the tail steps out but there is no need. Keep the steering straight, the AYC shuffles the torque, and you slingshot out of the corner.
Oh and beware stepping into a RWD car after getting used to AYC! You might have your work cut out catching the back end until you dial into it’s inherent ability to slide.