4" Variable Muffler — Pre-Order (8–10 Weeks)

HMD Fabrications Verified independent store

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Pre-order: ships in 8–10 weeks. Every muffler is hand-fabricated in the order it's booked, so your purchase reserves your build slot. You'll get updates as it moves through the fab shop. The HMD 4" Variable Muffler gives the driver full control over exhaust noise from inside the cab. An illuminated toggle switch wires through a heat and water-resistant harness to an electronically actuated valve. Open it up for a deep unrestricted tone. Close it down for towing, daily driving, and early starts. Precision TIG-welded from 304 stainless steel and back purged so the inside of every weld stays clean and corrosion-resistant. Simple, tough valve design built to run hard and hold up. Fits most 4" diesel exhaust setups. Show more