This feature can be programmed into the ECU on some petrol vehicles which results in a pop and bang or crackle noise coming from the exhaust system during engine deceleration. Many manufacturers already implement such a feature from factory on some performance models. The feature offers no performance advantages but does offer a sportier feel and noise.
Please check if this is available for you car.
Warning: This Upgrade should only be implemented onto vehicles which have a decat fitted to their exhaust system!