HKS Legamax Premium Cat-Back Exhaust - 2017+ Honda Civic Hatchback (31021-AH004)

Regular price $1,259.02 USD Sale price $1,259.02 USD Regular price $1,610.00 USD
Sale 21.8% $350.98 USD (21.8%)
In Stock!
SKU: hks31021-AH004
Product Description

Legamax Premium mufflers offer the performance benefits of a sports muffler with the class and elegance of a premium muffler. Every tailpipe design is customized per application to ensure that the muffler has impact and becomes a focal point in the appearance of the vehicle, yet blends with the overall design of the car. Legamax Premium mufflers are constructed of SUS304 grade stainless steel to give a high luster finish that is durable. The new 2017+ Civic Hatchback application comes with titanium dual tips. It was designed to be as straight as possible providing a 50% reduction in exhaust back-pressure to support more power modifications.


  • This product was previously released as 31021-BH002 Since the fitment to the JDM model was confirmed, the part number was changed to 31021-AH004. Also, this product is designed based on JDM and USDM models. Please confirm the model available in your country before purchase.
  • Civic Hatchback only with 1.5L Engine


  • Honda Civic [FK7 - Hatchback non Type R] (2017, 2018, 2019, 2020, 2021)


  • Full straight structure to improve exhaust flow
  • Tested and JASMA approved
  • Made of high-quality SUS304 for durability
  • Back-pressure reduced by 50%
  • Meets a standard for Japan's noise level regulation
  • Cat-back system includes Midpipe
  • Center exit design with dual titanium tips
  • Designed to eliminate exhaust drone
  • Made in Japan


  • Type: Cat-Back Exhaust
  • Piping Diameter: 60mm to dual 50mm
  • Tip Diameter: Dual 97mm
  • Material: SUS304 Stainless Steel Piping
  • Chassis Codes: FK7
  • Engine Code: L15B
  • Idle Sound: 61 dB (stock 53 dB)
  • Sound: 87 dB (stock 80 dB)
  • Pieces: 3-Piece System
  • Notes: 5mm less ground clearance than OEM
  • Warranty: Manufactures Warranty

To provide faster delivery and turn around time; Kami Speed ships products out from different warehouses throughout the United States. Usually averaging 1-4 business days for processing prior to shipping.

Depending on the package, we ship using different carriers according to the item's location, content, and size.

Freight truck items, will require up to 7 business days to ship due to size. i.e. hoods, trunks, body kits, etc.

All orders made after 3:00pm ET will be shipped or processed the next business day.

Orders over $500 will ship insured and over $1,000 with signature and insurance in order to guarantee delivery. Orders over $1000 may not be able to ship to a different address not listed as the billing address or confirm payment address from the form of payment used. Orders with suite numbers or apartment numbers will require signature if valued over $200.

All international orders outside of the USA are subject to duties and taxes per your countries jurisdiction and determined by customs.
Kami Speed serves the right to ship using an alternative method if we see it fit, in order to expedite shipping and reduce your rate depending on product value.

In stock, non special order items can be returned within 30 days of the product arriving to your house or place of work.
Returns will NOT be accepted on Clearance Items, Final Sales, Special Orders, Opened, Installed, Incomplete, or Otherwise Used Products. In order to initiate a return, an RMA number must be requested and approved via e-mail. All returns will be subject to a 20% restocking fee minus complete shipping cost (roundtrip).

Any processed orders that have not shipped will incur a 6% cancelation refund fee unless the product was not available to ship within a timely manner. No fee will be incurred if used as store credit.

For complete details on our return policy, please see our Help and FAQ link under HELPFUL INFO.

WARNING: Operating, servicing and maintaining a passenger vehicle or off-highway motor vehicle can expose you to chemicals including engine exhaust, carbon monoxide, phthalates, and lead, which are known to the State of California to cause cancer and birth defects or other reproductive harm. To minimize exposure, avoid breathing exhaust, do not idle the engine except as necessary, service your vehicle in a well-ventilated area and wear gloves or wash your hands frequently when servicing your vehicle. For more information go to