In general, any vehicle enhancement not made at the factory is considered a modification and requires custom vehicle insurance. Common modified or custom elements include:
Aesthetic modifications such as chrome bumpers, special lights, custom paint jobs, and new stereo systems
Performance modifications including suspension enhancements, strut bars, or engine turbochargers
Since these parts or features aren't typically fully covered by a standard auto policy, you may need to add an endorsement to your auto policy or buy a custom car insurance policy. Some insurance companies won't provide insurance for modified cars if they exceed certain criteria, like if the engine's performance is seriously enhanced or if custom paint jobs or decals significantly increase the vehicle's overall value.