BMW showed the 1-Series performance kit at the Geneva Motor Show in March. It’s probably as close you’ll get to turning your 1-Series into the tii concept; of course it would probably cost you a lot of money.
United BMW of Gwinnett, GA., was kind enough to post this video in which they compare the BMW 135i with the BMW Performance Exhaust to the regular BMW 135i. Installation takes about 30 to 60 minutes. You will basically have to cut the first set of resonators off and replace it with the piping and muffler provided with the BMW Performance Exhaust Install kit.
Click through for the video.