question about R143

Im curious to know why the mta decided to go with ad tranz propulsion for there R143 instead of the siemens, In my opinion it sounds much better and more futuristic. Does any one know why they decided to change the propullsion package to ad tranz? For people who dont know, The R143's pre 2004 era had siemens propullsion, although they completely changed it to ad tranz, Heres how the siemens sounded like.

http://www.youtube.com/watch?v=f5txGoS_iXg

http://www.youtube.com/watch?v=s00XKBbNTRc