I'm always so fascinated by the sound of emergency brakes on any train, whether the sound or the sight, it would be nice to see some more sound effects besides just emergency brakes get added to the game.
On the American freights I find it disappointing without the signature air swoosh as the air gets dumped and the breaks apply. Another thing needed to be added is the GE air compressor sound when the brakes are released on the ac4400cw.