The problem with the xi is the ride height but also the spring and the spring constant being used. It is way too soft. Most sport springs are "stiffer" linear or progressive. I also think our shoocks/struts suck too. Don't get me wrong, the entire suspension sucks as a whole.
If I had a winter vehicle I wold have got an E92 and and not an e90 xi.
The KW kicks ass because the spring is optimized to work with the shock. The shock is "jetted" as a sport shock.