Yoshimura R&D of America, Inc.

SOUND INSERT KIT RS-4 Muffler, 1.500" RING (INS-21-K)

SOUND INSERT KIT RS-4 Muffler, 1.500" RING (INS-21-K) - Main image
$25.39 $40.95 In stock

Category: Replacement Service Parts

  • Replacement Low-Volume Insert Kit for RS-4 Mufflers
  • Non-Spark Arrested
  • Available as optional kit on applications requiring different sound restrictions
  • Decibel reduction depends on application
  • Please see our Insert Chart to confirm fitment for your application
      • Kit Includes:
    • Low-Volume Insert Tube
    • End-cap collar
    • Set screw

*If you have any questions about fitment or applications, please call our Sales Department at 1-800-634-9166.

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Standard Shipping: Handling (business days) 0–1; Transit (business days) 7–15.

Express Shipping: Handling (business days) 0–1; Transit (business days) 7–15.

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Delivery costs

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Standard Shipping · United States: $0.00

Express Shipping · United States: $3.99

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Returning an item

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United States · Return window (days after delivery): 30. Return method: By mail. Return postage: Seller pays.

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Customer Reviews (4.8 / 5 · 5 reviews)

Robert G. ★★★★★

Was a bit wary of losing too much sound, but this insert kit dropped the noise just enough for my neighborhood without killing the tone. The ring fit snug into the RS-4 muffler and the swap was straightforward. Exactly what I needed for a quieter ride.

Harper T. ★★★★★

Took about ten minutes to swap the old insert for this low-volume kit, and the decibel drop is exactly what I needed for my quiet neighborhood. The ring fit snugly into the RS-4 without any wobble, and it’s held up through a couple of rides so far.

Scarlett ★★★★★

Had to swap out the stock insert for this low-volume kit because the noise at my track day was borderline. The 1.500" ring fit perfectly into my RS-4 muffler and definitely tamed the bark without killing all the tone.

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