For any suspension geeks out there who care, a minor update on my suspension geometry. As stated on the post above, for my car with this combination of parts and ride height, I am currently running 15mm of scrub radius with my parts combination. This is excellent for steering feel, providing good steering feel without excessive torque steer or side scrub. I will be testing out a 10mm spacer for the car, to see if I like the feel with the increased scrub radius. This would increase the scrub radius to 25mm of scrub, or 1 inch. I was tempted to test a 20 mm spacers (which would increase my track width almost an additional inch per side) but decided against it to keep my torque steer to a minimum. I feel just under one inch of scrub is a decent compromise between steering feel, torque steer, and track width.
My lateral instant center is now about 104" from vehicle centerline, and 74.6 inches from wheel centerline.
Roll Center height is 4 inches above the ground.
KPA is 15 degrees
Hopefully this helps those interested in modifying their wrx suspension for handling make some informed decisions. All measurements were done with the vehicle as is, without the 10mm spacers. Obviously, the spacers would change the measurements some. I am also contemplating grinding on my strut housing to enable more camber to be adjusted at the shock, and less negative on my camber plates, which would reduce my scrub radius slightly and my sai. All of this would again slightly change my final measurements. I will post up my final end product when I decide which I want to do.