I have the OEM wheel locks on my car and have to say that if I were a thief - they would not slow me down much if at all. The entire shaft of the wheel lock is fully exposed. If you do not have the key, simply grab onto the round shaft with a vice grips and crack them loose - then spin off with your fingers...
There has got to be a better way to secure the wheels..
When I got my wheels put on at Discount Tire here in town they said that the Ford wheel locking kit wasn't very good also like Big-Foot said. I bought a kit from them for like $25. It is very good quality.