While you're crawling around under the car, take a look at the front control arm bushings and the rear trailing arm bushings. Depending on the mileage, those may be in need of some attention.
I really like the Tree House Racing front control arm brackets and bushing on my car, but it looks like those are NLA, and Bimmerworld now actually has a slightly cheaper alternative--
http://store.bimmerworld.com/bimmerw...nts-p1301.aspx
They also have a bearing set to replace the rear trailing arm bushings. I don't have any first hand experience with these though.
http://store.bimmerworld.com/bimmerw...kit-p2138.aspx
Before I refreshed the RTABs and put in companion limiters, I got a kind of "wiggle" out of the rear end between when the chassis finished rolling and the rear end took a set. Went away when addressed.
Other track related suspension wear issues I've had over the 90,000 total miles I've put on the car are a rupture in the driver's side strut bearing and the inner ball joint on the same side front control arm-- seems to be more right turns than lefts at the track.
Strut bearing issue addressed by installing adjustable camber plates-- not much to do about the ball joint except replacement.