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USD 509.72
Part #: AFE49-14003NM

AFE 49-14003NM Large Bore HD 4" Downpipe-Back Exhaust (No Muffler)

2001-2004 GM 6.6L Duramax (All Cabs & Beds)
Part #: AFE49-14003NM
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The AFE 49-14003NM Large Bore HD 4" Downpipe-Back Exhaust (No Muffler) for the 2001-2004 GM 6.6L Duramax is engineered to perform in the most extreme environments. Constructed from precision, mandrel bent 4” 409 stainless steel tubing the large diameter tube and smooth transitions are specifically designed for maximum flow, increased horsepower, increased torque and lower EGTs. To provide a leak-free seal, OE style band clamps are used that offer a 360º sealing area vs. cheap U-bolt clamps used in other systems. LARGE Bore HD exhaust systems are the perfect combination of performance, fit and value.

Installation is a Snap:
All systems use factory mounting locations providing stability and a hassle-free installation.

Leak-Free Seal:
High quality OE-style flange and band clamps are used for a complete 360 degree sealing surface.

Aggressive Sound:
A muffler-delete pipe is used for a true race-inspired sound and maximum flow.

OE Fitment:
OE-style hangers with bayonet tip are used to maintain a stable pipe location during high vibration and high heat conditions.

Flow and Performance:
LARGE Bore HD exhaust systems are constructed of 4" mandrel bent stainless steel tubing for maximum flow. Smooth transition bends allow for low turbulence, increasing horsepower, torque and lowering EGTs.

  • 4” Mandrel Bent 409 Stainless Steel 
  • Muffler Delete
  • OE-Style Band Clamps for Leak Free Seal
  • Hassle Free Installation
  • Made in the USA
Application Note:
Tip Not Included

2001-2004 GM 6.6L Duramax (All Cabs & Beds)


  • MFG. Number 49-14003NM
  • Manufacturer Name AFE
  • Shipping Weight 64.00 lb.
  • Shipping Length 60 in.
  • Shipping Width 19 in.
  • Shipping Height 14 in.
  • Fuel Type Diesel
  • Diameter 4"
  • Exhaust Exit Single
  • Exhaust Type Downpipe-Back
  • Material T409 Stainless Steel
  • UPC 802959491706
  • Warranty Yes
  • Warranty Info 2 Year
  • Prop 65 WARNING: Cancer & Reproductive Harm -


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Questions and Answers

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Most Popular Questions

How does this fit all cab & bed lengths? I have crew cab & 6.5' bed.
View Staff Answer 
The AFE 49-14003NM Large Bore HD 4" Downpipe-Back Exhaust System (No Muffler) fits all cab and bed configurations with one kit because it includes a cut-to-fit mid-pipe.

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Emissions Notice

This product is not legal for sale or street use in California. Certain aftermarket products are subject to governmental emission standards regulated by the California Air Resources Board. In order for these products to be legal on a specific vehicle in California, the part number must receive a CARB Executive Order (EO) number. This number makes the part legal for use only on specific years, makes and models of vehicles. A decal with CARB EO number for these parts must be displayed in the engine bay to satisfy smog inspection requirements.