Forget what I said, I was thinking in terms of a raised car not a lowered car.
Never the less, lowering the car will get the bump steer past the apex which makes it worse.
If you look at the diagram, the stock suspension is the green arc. As the suspension is compressed you can see the angle change indicated by the arc. The normal suspension travel is located in the yellow circle .
If you add the bumpsteer shim, the main suspension travel crosses the apex of the bump steer arc and seems less of a problem. You can see what happens in droop. It gets worse quick.
If you lower your suspension your travel now falls in red circle so you can see how bump steer is magnified when you lower the suspension:
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