thanks all for the excellent responses. the longacre article is good information; I looked at that a few days ago.
here's a link to the rennlist thread which was also helpful:
https://rennlist.com/forums/996-forum/1186896-for-those-who-ve-adjusted-front-bumpsteer.html#post16503630
my suspension is really a street setup- H&R sport springs with Bilstein B8s; it's not coilovers, so ride height is not adjustable. Similarly, the sway bars are stock non adjustable. The only adjustments are front toe and bump steer, rear toe, and GT3 front control arms for additional camber.
I've raced with BMWCCA for about 5 years so I have a lot of track experience, but I think my problem is a tendency to turn in too early and hit the apex early or midpoint which means sometimes breathing the throttle on exit to get the nose to turn. It depends on the turn, but generally higher speed turns. So my sensation of "understeer" might be a combination of poor turn in and suboptimal car setup as well