I first thought my TDi MIGHT need a rear anti-roll bar but wasn't convinced of the need after several reasonably paced cruises.The built in understeer meant over commitment into a turn could be safely handled even if some mid corner braking was required.
After fitting a Bilstein cup kit and a few track days, I don't feel the car needs it at all (at the limit I can get some some mild lift off oversteer to help point the car) unless the GTi has a much stiffer front anti-roll bar than TDi. Even then, you could try a lighter :eek: front anti-roll bar to adjust the balance by adding grip to the front rather than reducing it at the rear with a rear anti-roll bar.