I'm in agreement with TRF415boy.
Shims under the front block = Kickup/Pro-dive
Less initial steering, more mid to exit. This is mainly due to the extra castor caused by running the arms at an angle.
Shims under the rear block = Anti-dive
More initial steering, less mid to exit. Reduced castor angle...
Currently, your running almost 6.5degrees of castor (2mm under the blocks adds about 2.5deg, 0.8mm is roughly one degree). So for starters I would reduce that a bit, say to 0.5 or 1mm. 2mm is a lot to have...
See my above comments on what that does.
Other things to look into.
Stiffer rear anti-roll bar - with mentioning that the snapping out is worse without a roll bar, it could potentially be that the rear tyres are suddenly losing grip due to roll. Try a medium bar on the rear with the red springs to start.
Rear droop; try less, as this will reduce weight transfer to the front.
Tyres; I know it sounds daft, but how old are your tyres? Could be time for a new set... A lot of handling issues I know of can be traced to tyres that are long past their best.
Rear shock oil; Lower the weight in the rear shocks. Your using the softest springs in the range on the rear, and a hard set on the front... but both use the same weight oil
The trick with good shocks to get the damping rate matched to the spring rate. Unfortuantly, there's no hard and fast rule... although a softer spring tends to prefer softer oil, otherwise it'll become over damped (shock will have little or no damping effect, and feel hard). I'd try 25 or 30 to start in the rear. You could also try going back to the 2hole pistons like that, but personally I find the car waaaaay too bouncy with 2 hole pistons, 3 holes seem to work better (both front and rear).