The traction control in these are pretty good in the holdens it cuts power almost completely so you stay sideways and have no control till it straightens up (which sounds good in theory). Softer rear will get more power to the ground and maybe a little less sideways action. There's a few ways to control it, you can drive through it with no TC it will straighten back up as long as you have it pointed in the right direction. Or you can back off quickly then back on again quickly using TC or not, this way sounds good too with the turbo. There are other ways. Heavy cars these so you don't want to get it wrong to often.
Wheel alignment, make sure its 4 wheel alignment and the thrust alignment is checked which is the front to rear alignment. I have heard this is a bit of an issue with these cars, mine was way out when I first had it done. Check there is not to much toe in on the rears, that can cause the car to step out easier, just go neutral toe till you get used to it.