Frequently Asked Questions


  1. Q1.I hear a lot about penalty of vehicle height in Japan. How do you actually measure this?

    For there is no one in a car, measure the distance from the most low part(such as catalyzer or muffler) to the ground. But you can exclude the accessories like aero parts or mud guard. All HKS products pass this regulation of 9cm clearance, you don't have to worry about it.
    * The measurment is for a stock car. It could be difficult to have ground clearance if you have changed the height.

  2. Q2.Can I use inner silencer and still pass the safety standards?

    HKS MUFFLERS passed noise regulation without using inner silencer.

  3. Q3.How do you measure the close noise of exhaust?

    Close noise of exhaust is measured in a certain condition of engine at a certain RPM.

    1. Set the sound measument device at a 0.5m from the muffler exit of 45 degree.
    2. The engine RPM for the measurement has to be 75% of what the engine can produce.
    3. From the #2 situation, put the gas for 5 seconds with no pressure for RPM and release the pedal, and measure the sound while the RPM get to the idle RPM. And at this measuremnet, the highest sound is the sound of the test result.

    * This is the diagram of the tesing.

    Set the muffler as shown here

    The Lancer Evo's max power is at 6,500, so set RPM at 4,875 wich is the 75%

    Put the gas for 5 seconds at the 4,875RPM and start to measure the sound. After 5 seconds, take the foot off from the pedal and check sound until idling.

Structure & Warranty

  1. Q1.What's the difference between normal muffler and HKS muffler?

    Normal mufflers are made not to have any problem than to have efficient exhaust capability. And the HKS mufflers and pipe layout are designed to support the best performance of a car.
    Also the shell part of the normal vehicle is made to decrese the sound of exhaust gas but HKS shell is designed for a cool and sporty sound.

  2. Q2.What is the HKS warranty for the products?

    HKS provides a warranty to the original purchaser of HKS exhaust systems against defects in materials and workmanship for a period of one year. The warranty is available only for vehicle specific exhaust systems. Metal catalyzers, front pipe, exhaust manifolds, and center pipes are not covered.
    (For more details, please go to the product warranty site.)

  3. Q3.I bought a muffler about 2 or 3 years ago. And the sound of the muffler got bigger than before. Is it normal?

    The muffler passes hot air, so over the years the quality of the mufffler sound will drop and will have a bigger sound.
    Muffler is a consumable good. That's why we are using the advantex glass wool for the best and long lasting mufflers.

  4. Q4.What is a cylinder in the middle of the pipe of HKS MUFFLER series?

    That's called a " SILENT CHAMBER (ex: ES WAGON 409)".
    A stock car, mini van or wagon tend to have a muffled sound when you change the muffler, and the silent chamber make this muffled sound go away.
    As you can see below, silent chamber can change the frequency and reduce the bad sound from the muffler.
    We test and analyze the each vehicle's sound and make a best silencer. However by putting this chamber will not effect on the exhaust presure and the beauty of the car.

For sport user
  1. Q1.I am driving a NA car and I was looking for a muffler that makes sounds like NA, does HKS has such a muffler?

    The HKS SUPER SOUND MASTER MUFFLER is perfect for you. It has a cool high pitch sound and at a low pressure and has a quiet sound.

  2. Q2.I changed the sport turbine kit and I am looking for a muffler for my big powered car. ButI don't want a too loud muffler. Do you have such a muffler?

    Yes we do. HKS SUPER TURBO MUFFLER has a low pressure and lower noise muffler.

  3. Q3.I ofter go to circuit for driving. And I want a ultimate muffler for a ultimate car driving. Does HKS has a perfect muffler for me?

    The sport muffler that is made fully of titanium (one of the lightest muffler in the market) and ultimate straight design muffler HI-POWER SPEC R, HKS' top level muffler developed to attack in the circuit, is perfect for you.

  4. Q4.I want to buy a sport muffler but I can't afford an expensive one. Does HKS has a reasonable sport mufffler?

    Yes HKS HI-POWER 409 is good and reasonable muffler. It's HI-POWER series high quality muffler for an affordable price.

  5. Q5.I think it's very important to have a good perforamnce muffler, but recently the regulation has got more strict, so I want a muffler with quiet sound and still has a good performance. Does HKS has such a muffler?

    The SILENT HI-POWER as the name indicate, is the muffler with quiet sound and still has performance power in a good balance.

  6. Q6.I usually use may car to drive in the city and I don't need a sport muffler but I want a cool looking design and a good perforamnce.

    ES PREMIUM is a cannon ball type design muffler and LEGAMAX PREMIUM is the clean and stylish tip design muffler that are very cool and beautiful looking. It's a perfect for city drive of a normal vehicle.

  7. Q7.I have Skyline GT-R (BNR34) with the RB2.8L engine and installed GT2530KAI, Airflow Less Adaptor, V-Cam, etc. The engine output is over 600PS. The exhaust sound is very noisy, so I am worried if it is bothering my neighborhood. Is there any exhaust system which is quiet at low speed but still maintains high performance at high speed?

    "2 Stage Exhaust System" is recommended.
    Usually, as the tuning level is advanced, implementing "silence" and "high power" together may be difficult.
    But, the switchable valve equipped with this exhaust system controls the exhaust path depending on the engine RPM
    so the exhaust system can withstand high power maintaining silence at low speed.

  8. Q8.I have a sports car and look for a exhaust system made fully with titanium, but it is very expensive. Is there an affordable lightweight exhaust system?

    "Hi-Power SPEC-L" is recommended.

    Pipe plate is 0.8mm thick and silencer outer plate is only 0.5mm of SUS304 material. This super lightweight exhaust system is comparable to a full titanium made. Also, it has an efficient exhausting ability and cool sound. Only HKS can make this kind of high engineering exhausting parts.
    *Subaru WRX Sti: The weight of this SPEC-L is only 10.5kg which is -53% of the 22.4kg stock exhaust system.
    The lightweight exhaust system has many advantages such as better exhaust efficiency, acceleration/deceleration performance improvement, reduction in a brake load, more accurate turning traceability by reduced inertial weight reduction, etc. Replacing the exhaust system with this product changes the driving drastically.

For Mini Van & Wagon User
  1. Q1.I owe a mini van and want to have a muffler that fits to my van which already has the aero and the aluminum wheel and still has quiet sound. And still it has to be a good looking muffler. Do you have a muffler for me?

    LEGAMAX PREMIUM is what you need. It fits great for a van with the aero and aluminum wheel installed. And of course it has passed Safety Standards regulation for a sound level.

  2. Q2.I am looking for a muffler that has sporty performance features and sound for my wagon. Does HKS has a cool sporty muffler for a wagon or mini van?

    We have develpoed a new cool and stylish design of muffler ES PREMIUM or ES WAGON for a users who are looking for the sportiness in their muffler.
    * We also have a low cost muffler ES WAGON 409

  3. Q3.I want to change the muffler for my car. And I want something with decent performance and looks good and cheap! Am I asking too much?

    No, not at all. We have exactly what you want! The LEGAL MUFFLER is what you are looking for. Its tip is designed for the each vehicle and have a good feature for a low price.
    * There is also LEGAL MUFFLER SPORT.