A few weeks ago I managed to get a friend of mine, who has exactly the same car as mine (116i Auto, Sport Line) to come along and test the two cars. I had the Hartge tunning box pluged in and his car was stock. Both cars are well run in (more than 7.000 kms), and also note that we had done another test, when both car were stock and we were on par.
So here is the video, where you can see the difference between the two cars: