LIGHTS. Those blue-white, high-intensity discharge headlights can really dazzle -- especially when they're coming right at you. New ones go for $500 and up per light, sometimes $3,000 per car.
AIR BAGS. You gotta have 'em, but companies say that 10% of all theft claims involve an air bag. The driver's side bag, mounted in the steering wheel, is the easiest to remove and costs $500 to $1,000 to replace.
WHEELS. Custom rims are the easiest way to give your car a flashy new look, especially the "spinners" that keep revolving when the car is stopped. They go from $100 each up to $15,000 for a set of super-luxe models.