I also feel the front a bit heavy on the X. That, plus the fact that all manufacturers 'tune' their cars to have a tendency to understeer (safety reasons for the average driver), the X will have a tendency to slip from the front at it's limit (quite low on snow or under rain).

From my little experience playing with suspensions, I found on my E30 (325ix), that had a big understeer problem under rainny conditions, that installing a bigger rear sway bar helped a lot. I went from a car that was not able to keep the pace with a RWD under rain, to a AWD monster with lots of traction in turns :-)
I'm not expert on suspensions, but I think that stiffening the rear, will transmit some weight on the outside front wheel and make the grip better.

It's not on my priority list because my X is a family vehicle, but may be one day I will install a bigger rear sway bar for a better feeling.

Oh, FWIW, when I want to have fun with the X on snow, with the DSC OFF, I found that turning the steering wheel more than needed will help the rear to go around (half turn instead of quarter of a turn for example + some gas).

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