Key facts
- Check the chassis code, engine code and market before you buy any performance part. Fitment decides whether a part works at all.
- In California, most performance parts that affect emissions need a CARB Executive Order before they can be used on a public road.
- Under US federal warranty law, a manufacturer generally cannot void your warranty only because you installed a part from another maker.
Japanese performance parts are aftermarket components made by Japanese tuners and factory performance divisions. They cover engine, intake, exhaust, suspension, cooling and electronics. The part is only useful if it matches your exact model, engine and market, and if it is legal where you drive.
How do you confirm a performance part fits your car?
By Toda Namiki, Editor, Japanese Auto World
Match the part to your car's chassis code and engine code, not just the model name. One model often ships with several engines and more than one market version.
- Find the chassis code on the vehicle's data plate or in the owner's documents.
- Confirm the engine code, because one model can use several engines.
- Check the market. A Japanese-market car can differ from a US-market car in emissions equipment and electronics.
- Ask for the part number and the maker's fitment list, then compare the number on the box with the list.
- Reject any listing that says "fits most" without a model and year.
For how Japanese auction sheets are read, see the Japanese auction guide.
Which Japanese performance brands are known for what?
Each brand specializes in a different area. Start with the brand that makes the category you need.
- HKS: turbo kits, exhausts, intakes, engine-management electronics, suspension and cooling parts.
- GReddy: exhausts, turbo kits and blow-off valves, intercoolers, air intakes and electronic controllers.
- Mugen: a company separate from Honda, founded in 1973, that builds performance and styling parts for Honda and Acura models, including wheels, suspension, exhausts and body kits.
- Tein: suspension, including lowering springs and OE-shape shock absorbers.
- Cusco: suspension parts and coilover kits, including kits for specific models such as the GR86/BRZ.
- TRD: Toyota's performance and accessory division. In the US it is best known for off-road accessories.
- NISMO: Nissan's official performance brand, offering parts, vehicle set-up services and road cars such as the Fairlady Z NISMO.
Brands change their model coverage, so check each brand's current fitment list before you order.
Are Japanese performance parts better than other aftermarket parts?
Not automatically. Some lines are developed and tested on the cars they fit. Others carry a famous name with little testing behind it. The useful test is the part number, the maker's compatibility list, and owner reports from people who run the same car you do.
Factory performance lines, such as TRD and NISMO, come with the manufacturer's engineering and warranty terms. That counts for more than reputation when a part touches the engine or brakes.
Which upgrade should you buy first?
- Brakes and tires. Better stopping and grip come before more power. A car that accelerates faster than it can stop is a worse car.
- Suspension. Coilovers or a lowering kit change how the car turns and rides, and they usually make the ride firmer.
- Intake and exhaust. These are the most common bolt-on parts. The gains are modest alone, and some engines need a tune to use them safely.
- Engine management. When airflow changes, the fuel and ignition maps must change with it. Running lean or detonating can destroy an engine.
- Turbo or supercharger. Add these last, with fuel, cooling and drivetrain sized to match.
For more on modifying a Japanese car in order, read the JDM modification guide.
Are performance parts legal in the United States?
Federal law forbids removing or disabling emissions equipment on a road vehicle, and the prohibition lasts for the vehicle's whole life. The EPA treats aftermarket hardware or software as an illegal defeat device when its main effect is to defeat emissions controls. Engine-control tuners, parts that block exhaust gas recirculation, and straight pipes that replace catalysts all fall into that category. Any part that changes the onboard diagnostic system can also be illegal.
California goes further. Performance parts such as headers, tuners, intakes, superchargers and turbochargers generally need a California Air Resources Board Executive Order before they can be sold, installed or used on a public-road vehicle there. Parts without one may be sold only for a racing vehicle, and the seller is expected to label them as illegal on public highways. A label does not protect a seller or installer whose customer drives the car on the street.
State inspections can also fail visible changes, such as an exhaust that exceeds the local noise limit.
This is general information, not legal advice. Confirm the rules for your car with your state DMV or emissions agency before you buy.
Does an aftermarket part void your warranty?
Not on its own. The FTC's position is that a manufacturer generally cannot void a warranty or refuse a claim because the owner used a part made by someone else. Two exceptions apply: the company supplied the part free, or the FTC granted a waiver after proving that the product works properly only with the named part. Even without a waiver, a company can deny coverage for a defect or damage that the aftermarket part caused.
Keep the receipts and the part packaging until the install is tested.
What does a performance upgrade cost?
The part is often the smallest line on the bill. The total depends on the parts you choose, the tune, installation, alignment, inspection and the extra fuel and maintenance that more power requires. Price ranges change with the model and year, so check current prices for your exact car before you set a budget.
Frequently asked questions
Are Japanese performance parts better than American ones?
Not as a rule. Quality depends on the brand, the specific part and the testing behind it. Judge the part by its fitment data and owner reports for your car.
Do Japanese performance parts fit US cars?
Some do. Japanese-market and US-market versions of the same model can differ in engine, emissions equipment and electronics, so check the chassis and engine codes before you order.
What is the best first performance upgrade?
For most street cars, brakes and tires come first, then suspension. Power parts come after the car can stop and grip reliably.
Can I use a Japanese performance part on a US public road?
Some can. Any part that affects emissions needs a legal status check before installation. In California, most such parts need a CARB Executive Order. Parts labeled for racing use only are not legal on public roads.
Will a performance part void my warranty?
Not by itself. The manufacturer generally has to show that the aftermarket part caused the failure before it can deny a claim for that failure.
Is an aftermarket exhaust legal in California?
Only if the exhaust has a CARB Executive Order for your vehicle, or if it is sold and used strictly for a racing vehicle that does not run on public roads. An exhaust without an Executive Order that you drive on the street is not legal there.
About the author
Toda Namiki is an editor at Japanese Auto World. Toda has written about used Japanese cars for more than 20 years, working directly with car exporters in Japan and with auction agents, and knows how vehicles are sourced, bought at auction and exported.
