Teuton,
Sorry for the delay, i've been out of town for the past few weeks. The word from Sachs NA is that there should be no machining and that it is a direct bolt on replacement.
I am going a different route - I am going to install a custom aluminum flywheel built by VAC motorsports. The lightweight flywheel weighs only 11 pounds, versus the 38 lbs for the stock dual-mass unit. There is going to be some flywheel chatter at idle, but I am willing to make that trade off for quicker response. Since I track my car, I would like to be able to heel-toe quicker, which is not possible with the heavy dual-mass flywheel.
If anyone else is interested
www.vacmotorsports.com
Check them out