Well there's a bit more news in that the 1.6 will likely need new injectors and the others will need "new software".
Anyone know why injectors would be the thing here? I assume each injector has a min/max flow so is it possible that the 1.6 injectors can't go low enough or something? Both have similar injectors after a quick google, piezo 1600/1850 bar / 8 nozzle but there will likely be more differences im sure.
Spray pattern / atomisation characteristics.