taipan53,
First, here's a page that gives what I think you are asking for: info about the various AGR racks ->
Ford Applications - AGR Performance - MB Motorsports
You can compare the two.
I admit to being curious about why you think this would affect "oversteer?" Maybe you are using the term differently; it usually refers to the response of the car to a throttle and/or steering input, not the ratio of the rack itself.
Tom