exhaust temps are lower. Porsche probably has some development that lets them do this, but it probably won't appear on other apps. for a few years. There are older cars that tried this(89 Chrysler Shelby CSX, 90 Le Baron GTC, Shadow ES, and Daytona Shelby) US market VW tdis and Non-us audi and mercedes use vnt, as seen below from a VW 1.9T diesel