I suspect that the castor angle has changed a few times to be honest. I was informed that it was reduced around 2006 when the damper blades were dispensed with. That was also around the time that the Devol bushes went and the stubs had the track rod ends moved from top to bottom on the steering arms.
All I can say is that castor return us much stronger on my 05 Roadster than my 16 GDI. Its very obvious.
