Harrison wheel alignment

[sambo]

I know there are plenty of suspension-related threads out there but I have some specific questions about the Harrison setup with R33 rear end.

After giving up on the big brand tyre places, yesterday I had a proper wheel alignment done at Traction Tyres here in Melbourne. Very knowledgeable, passionate about their trade and two of the technicians have R33 Skylines, so they're familiar with the Harrison IRS.

So now the car tracks straight and true when launching/stopping hard and the stance is finally looking good with an even 4" clearance around the floor pan. It's a pleasure to drive compared to the "Bridgestone boys" setup.

One niggle though - when cruising in a straight line, if I move the wheel slightly left or right it wants to dart off in that direction. I wonder whether I have too much toe in?

Final settings (in degrees/minutes or mm):

Front (L,R)
Camber: -1.34, -1.23
Caster: 2.24, 2.05
Toe: 0.9mm, 1.0mm

Rear (L, R)
Camber: -1.17, -1.22
Toe: 1.6mm, 1.5mm

I wanted more caster but the front left upper A-arm is wound out to the end of the bolts. Without changing the bolts, more caster will introduce excessive neg camber. Right hand side had plenty of room to move - crooked geometry?

I'm running 17" wheels at 30psi, not sure whether lowering the pressure will help with stability?

Fire away brains trust!