Another modification I made was to put in a reversing Aid with real voice.
When you back up parking or to a wall or any other object the unit will tell you in a nice friendly female voice how far away you are from an object.
It starts out by 8 feet and tells you the distance down to 12 inches.
Attatched are two pics which shows the sensors on the car and the location of the speaker inside.
Information about the Module can be obtained
here
Sensors 
Speaker
I know I am Gadget Freak but hey, it's all good. Enjoy