I have PSS, but in winter time I run Dunlops that generetes more wheel spin - true. Some poly bushes and torque arm insert as well installed already. I tried many settings in XDS (weak, standard, strong), also changed VAQ into "increased traction" in module 32. I can say that changing to increased traction helped a little, but didn't cure. I also have the feeling that something might be wrong with suspension and it tends to twist into right under hard acceleration even without esp/xds intervention - no wheel slip. BTW, do you know what does "Haldex clutch status - degree of blockage" mean in advanced measuring module 32? Maximum value i was able to achieve was 24,8% and it locks up even when car is in neutral and i press hardly accelerator.that power is above what the car can cope with with out any wheelspin...
Usually you should try the best tyres Conit sport contacts or PS4,s...then suspension etc ..
You can reduce the intervention of the XDS (ESP light) by adjust a setting in the ABS unit (labelled expanded difflock) to "weak"...this will allow the VAQ unit to do its job better.
when you spin the wheels..the left (when sitting in the car) wheel will spin faster then the right one as the VAQ unit is on the right side of the gearbox....& the left drive shaft is lighter shaft is therefore spins easy..the right drive shaft goes through the VAQ unit & has the extra weight/mass of the clutch's to spin therefore slower... before the ABS sensors tell the VAQ to operate..