I thought some might like to see the solution which we used for this... We ordered these pieces:
http://www.breezeautomotive.com/details.php?prod_id=811
When you remove the boots from the ends of the rack, you will find that most likely, there is already a spacer/stop in place. On my car, we left the original stop in place on the driver's side and added the above new stop. On the passenger side, we removed the original stop and replaced it with the new one. The steering stops just about perfectly now!
Here is a picture of the 2 stops installed:
