[Tambohamilton]

Is it an XD? If not, I suspect you actually have an 11mm rear sway.

2" is pretty low IMO, especially assuming you're coming from m-sport? I'd go no more than 1" lower than m-sport, personally.

I'd move closer to 0 rear toe, though that likely won't help much mid-corner.

The position of the car's COG relative to the roll centre (well, roll axis) defines how much roll torque is generated by a given cornering load. Roll torque is what the suspension has to counteract to keep the car flat in the corners (maintaining decent camber etc). If the roll centre (and therefore roll axis) height varies wildly with suspension movement, it results in fluctuating roll load on the suspension disproportionate to the change in cornering load...resulting in big changes in grip from small suspension or control inputs.

This roll centre thing is likely why the e9x responds positively to having an oversized front sway bar...but that's not to say that rear bar won't also help in a similar way!