@John and Easy: im pretty sure that the rear track width is the same on a GTS as compared to a C4S. I dont think that there is any difference in the suspension set up in the GTS compared to the other PASM equipped cars.

Had a chance to drive the -20mm Sport PASM car today for like 5 mins (was a customer car) at my dealer. Its definitly not as stiff as i was concerned, had the feeling that the car was more planted and stable even at slow speed. Other than that i cant say that much, because the drive was too short. But definitly looks better with the -10 mm compared to the PASM.

@Reginos: thanks for the input, while i think i can live with the stiffness, now kinda concerned about the trim rattles...

i can change the specs another 7 days: this is going to be tough...

thanks for the input.