Big rear bar = oversteer right?

[Craftsman]

So the Anti-sway bar prevents body roll by being a large spring that resists movement of the suspension arms.

[Drift For Food]

It doesn't prevent movement of the suspension all together. It simply resists the difference in suspension movement on both sides. For example, your suspension can be fully extended or compressed way down. If both the left and right side are the same, the swaybar does nothing. However, when you try to move one side different than the other, the swaybar acts like a spring resisting the difference in movement between both sides. For example, if you run over a curb with your left rear tire, the swaybar will actually try to lift the right rear up to match how much the left rear went up. How much the swaybar affects the right rear tire depends on how thick it is, the thicker, the stiffer.