[Dean]

Originally Posted by AtomicLabMonkey

This is a bit of a misleading statement; angling the LCA's down towards the chassis is typically bad for handling, but not for the reason you're describing. The negative camber gain in bump does get smaller as you angle the LCA's down, but it is not an on/off switch like you make it sound. The wheel will still have negative camber gain in bump up to point where the LCA is perpendicular to the steering axis.

The dominant effect is the change in front view swing arm length, instant center locations and corresponding changes in roll center location & stability. These parameters are very sensitive to LCA angle. Changing the chassis pivot height even 1/2" can mean the difference between a stable roll center as the suspension articulates, and a roll center that swings wildly around outside the car as the instant centers pass through asymptotes.

I don't believe what I am describing is misleading at all, or incorrect for the macpherson strut front suspension on the Impreza, and the way the attachment points are configured. I am not discussing the chassis pivot at all, as it cannot be adjusted, and am focused solely on dynamic camber as it relates to ride height.

Due to the fixed top connection point on strut type suspensions, and the relatively short front LCAs on the Impreza; as they travel thought their arc from

_
  \
to
_ _

to
_ /

Under compression, they go from gaining negative camber quickly at the bottom to neutral to gaining positive camber quickly at the top. Ride heights controlled by the strut adjustments determine where in this range the LCA operates.

The ride heights I linked to in general keep the LCA out of the extrmely high positive gain area near the top that people get into when they over lower the Imprezza front suspension, especially on soft springs.

Because they cannot change springs, or ride height The A Stock autocrossers have done a bunch of imperical testing, using ever larger front sway bars on the front of the stock STI up to the current huge 32mm bars with no rear changes to keep the stock front suspension from going into the bad positive range. On a car that already understeers, that sounds like lunacy, but the gains in/maintenance of front traction due keeping a properly negative camber and thus good contact patch while cornering far outweighs the negative effects of the stiffer roll characteristics on that end of the car.