Aftermarket headers and CARB EOs: what to look up

Do Aftermarket Headers Need CARB Documentation?

Quick answer: Headers deserve careful research: BAR's Smog Check Manual lists customized exhaust installed before the last required catalytic converter or other after-treatment part, including headers, as something inspectors check for a CARB EO. Look for the EO, the part number, and whether that EO lists your exact vehicle.

Why headers get attention

Headers sit upstream of the catalytic converter. CARB treats pre-catalyst exhaust components, such as headers, connecting pipes, exhaust manifolds, and turbine inlet and outlet pipes, as their own exemption category. CARB's enforcement advisory names exhaust headers among the performance parts that typically need an EO.

BAR's manual also lists exhaust manifolds among the "other emission related components" inspectors look at during the visual inspection.

Catalytic converters come along for the ride

Header work often happens near the converters. According to BAR's manual, inspectors check that all required catalytic converters are present, that there's the correct number, that they're in the original locations, and that they show no tampering or defects. A change in the number of converters is only acceptable when an EO allows it. Since January 1, 2009, CARB has required aftermarket catalytic converters installed in California to bear an EO number.

Factory look-alikes

BAR's manual points out that some vehicles come from the factory with tubular exhaust manifolds that look similar to aftermarket headers. If yours are original equipment, photos and paperwork showing that can save confusion.

Practical steps

1. Identify the part. Factory manifold, factory tubular manifold, or aftermarket header?
2. Find the label and part number. Check the under-hood product information label, any markings on the part, the box and the instructions.
3. Read the EO at CARB. Confirm your vehicle and your exact part number are listed.
4. Read the conditions. Note anything the EO says about other parts or required changes.
5. Record your converters. Photograph any converter labels, and note whether the header install changed anything near them.
6. Save it all with your receipt and the shop invoice.

Who decides

The Smog Check inspector decides at inspection. CARB answers EO questions at (800) 242-4450, and the Smog Check Referee handles disputes and unusual cases.

What Showgone can and can't do here

Showgone helps you keep header and converter photos, part numbers, EO numbers and receipts together, with a link to check the EO at CARB. Showgone isn't CARB, BAR, the DMV or a smog station, and a Showgone record isn't an official certificate.

Add this part to your free Showgone garage.

Not legal advice.

Sources

• BAR: Smog Check Manual (April 2025), Section 1.3.1 and Appendix C (table, footnote 4, Catalytic Converters)
• CARB: Procedures for Exemption of Add-On and Modified Part(s) for On-Road Vehicles/Engines (adopted June 29, 2021), Section III(a)(7)
• CARB Enforcement Advisory #292 (July 10, 2020)
• CARB: Aftermarket parts lookup
• BAR: On-Board Diagnostic Test Reference (Referee contact)

Date checked: 2026-10-20