i think your NA height might be just set too low. well, I haven't taken mine to the track like you, but even with the soft rate springs I got on the NA's I use the second from the bottom height. haven't had any understeer problems yet taking some fast corners (doesn't seem like I'm riding the bumpstops). oh yah, the soft rate springs raise the height about 3mm compared to the mediums that you got. the ride is still pretty darn low though.
