Haven't got a chassis number for a CSS yet. I should be able to see everything that's different on ETOS i hope, so people can upgrade GTi or CS models for specific parts. I did it for the CS to GTI PP and suprisingly only the springs were different, no change to mounts, ARB or dampers.
I didn't want to ask for someones chassis number as it would look a little odd, if you know what i mean, so happy to wait till one pops up via VRM lookup at work