http://www.car-engineer.com/suspension-design-definitions-and-effects-on-vehicle-behavior/ from the above they reckon -14mm, useful to know if one is thinking about spacers or different wheels. BTW little known point but one of the major reasons for negative scrub is safety, in a blow out the loading back through the steering and subsequent driver reaction is correct whereas for positive scrub one would tend to make the situation worse. This is something SAAB found a long time ago, I read it in one of their books about the history of the company and their R&D about 15 years ago.
Having had many highly modified Saabs I can concur. I'd say my tuned classic 900T16S would out handle my RS at the moment.
