Have you had the digital caliper out to conform the measurement yet madstaff?
It would be interesting to know.
The external diameter of GTI PP/CS/CSS are all, I think, 21.7mm, they're hollow bars and the difference is the wall thickness 3.0mm or 3.6mm.
5Q0511305AQ Anti-roll bar 18,5X2,5 PR-0BC,0BM
5Q0511305AR Anti-roll bar 19,6X2,6 PR-0BD,0BN
5Q0511305AS Anti-roll bar 20,7X2,8 PR-0BE
5Q0511305AT Anti-roll bar 21,7X3,0 PR-0BF
5Q0511305BA Anti-roll bar 21,7X3,6 PR-0BG
5Q0511305BK Anti-roll bar 19,6X2,6 PR-0BT