Lol .. this is all a big myth !!
The technical specs are the same - the only difference is 'as standard' the Digi has it's fuel and ignition maps setup with fuel consumption more in mind, and the throttle response isn't quite that of the K Jet - again to use less petrol. (Good old digi lag!)
Anyone ever been in a chipped Digi GTI ?? Not a huge amount of extra power but it's a different car, so much more drivable and responsive - in my mind the way they all should have been !!