Exhaust› Exhaust Pipes, Systems and Components

Milltek

Active Valve Cat-Back Exhaust System

$2,651.41

SKU: SSXFD420

In Stock
In Stock
Ships by Sep 13
Free Shipping over $200
$100 Minimum Order
30 Days Return
INSTALL DIFFICULTY
DIY PRO SHOP

Moderate — 2–4 hours

Overview

The Milltek SSXFD420 is a cat-back exhaust system designed to enhance the sound and aesthetics of compatible Ford Mustang models. It features active valve technology, an H-pipe center section, and GT-115 (4.5-inch) polished tips. Constructed from 304L "Aircraft" Grade stainless steel, this system is built for durability and resistance to harsh conditions.
Show original supplier description
The Milltek SSXFD420 Cat-Back Exhaust System is engineered for performance enthusiasts seeking to elevate their Ford Mustang's auditory and visual appeal. This system integrates active valve technology, allowing seamless transitions between quiet cruising and aggressive performance modes, fully compatible with factory drive modes. At its core, the H-pipe crossover section is designed to equalize exhaust gas pressure between cylinder banks, producing a deep, traditional V8 rumble that emphasizes lower frequencies. This makes it an ideal acoustic upgrade for owners of the 5.0L Coyote engine who desire a muscular and commanding exhaust note without excessive rasp. Constructed from premium 304L "Aircraft" Grade stainless steel, the SSXFD420 ensures exceptional longevity and resistance to corrosion, even in demanding environments. The system features high-flow, mandrel-bent tubing with a 3-inch (70mm) diameter to maximize exhaust velocity and reduce backpressure, potentially leading to performance gains. The visually striking quad 115mm (4.5-inch) GT-115 polished tips add a custom aesthetic. Installation is designed to be a direct replacement for the original system, with an estimated fitting time of 1.5 to 2.5 hours. The system comes with a Limited Lifetime Warranty, underscoring Milltek's commitment to quality. This cat-back system is specifically designed to fit the 2021-2026 Ford Mustang Dark Horse and Mach 1 models.

Product descriptions are provided by our supplier partners and may not always be perfectly accurate. Not sure this fits? or call (760) 282-4645 and we’ll verify before you order.

Fitment

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Specifications

BrandMilltek
Part NumberSSXFD420
CategoryExhaust

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Returns & Fitment

Built for enthusiasts. Every order is backed by our 30 day return window on eligible items. Unused and uninstalled products may be returned with approved RMA and no restocking fees when received in new condition. Orders placed through the MOTORMIA app with a complete build qualify for our Fitment Guarantee — free return shipping if the part doesn’t fit your exact setup. The guarantee covers fit only; installation must follow manufacturer instructions, and we recommend a qualified shop for parts marked Difficulty 4–5.

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Shipping

Orders are processed in 1–3 business days. In stock parts ship promptly from our partner network. Special-order items either aren’t currently stocked or are built to your spec — expect 4–6 weeks. If a part goes on backorder while your order is in the queue, we’ll reach out and work through discounted alternatives together.

Free shipping over $200 in the continental US. Alaska, Hawaii, U.S. territories (Puerto Rico, U.S. Virgin Islands, Guam, American Samoa, and the Northern Mariana Islands), and international orders carry surcharges — most appear at checkout. Some exceptions (LTL freight, or suppliers who quote freight only after we place the order) won’t. In those cases we’ll reach out with the exact charge before your order moves forward.

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