aFe Large Bore-HD 5 IN 409 SS DPF-Back Exhaust System w/Polished Tip 20-21 GM Truck V8-6.6L

The Large Bore-HD Cat-Back Exhaust System Built for Sound and Flow

The aFe Large Bore-HD cat-back exhaust system 49-44125-P is a precision-engineered replacement for your vehicle's restrictive factory exhaust, built from 409 stainless steel in 5" pipe diameter for reduced backpressure and genuine performance gains. Connects at the catalytic converter outlet and runs to the rear of the vehicle. The 49-44125-P is fully mandrel-bent for consistent interior diameter throughout every curve, preserving exhaust gas velocity from the collector to the tailpipe. The result is improved power delivery across the RPM range, a more aggressive exhaust note, and a polished stainless tip that improves the look of the rear fascia.

Key Features

• Material: 409 stainless steel, TIG-welded joints
• Pipe diameter: 5" mandrel-bent for consistent flow
• Tip finish: polished stainless
• Direct bolt-on using factory mounting points and hangers
• Reduces backpressure for measurable power and torque gains
• Aggressive exhaust note without excessive drone at highway speed
• All hardware and gaskets included for straightforward installation

Fitment

Specifications

What's Included

• aFe Large Bore-HD cat-back exhaust system (49-44125-P)
• All required clamps, gaskets, and hardware
• Installation instructions

Frequently Asked Questions

In most applications, a bolt-on cat-back or axle-back exhaust does not require a tune. If you are also running a downpipe or header, a tune is strongly recommended to fully realize the power gains and prevent any lean conditions. Always consult your tuner when building a full exhaust setup.

The aFe Large Bore-HD is designed to produce an enhanced exhaust note without excessive interior drone at highway speed. At idle and during spirited acceleration, the sound is noticeably more aggressive than stock. Sound level varies by vehicle platform and individual preference.

Yes. The 49-44125-P is designed around OEM ground clearance specifications. If your vehicle is lowered, inspect clearance at the lowest point during test-fit before final installation to confirm no contact with body or suspension components.

Yes. The 49-44125-P ships complete with all clamps, gaskets, and hardware needed for the installation. No separate hardware purchases are required for a standard bolt-on installation.

Gains vary by vehicle, engine, and supporting modifications. A cat-back exhaust alone typically contributes 5 to 15 hp on naturally aspirated engines. On turbocharged or supercharged applications, a full exhaust system combined with a tune can yield significantly larger gains.

Under the Magnuson-Moss Warranty Act, an exhaust upgrade alone cannot be used to void your powertrain warranty unless the dealer can prove it directly caused a specific failure. For any drivetrain or emissions-related service, discuss this with your service advisor before work begins.

The 49-44125-P comes with its own polished stainless tip. If you prefer different tips, the pipe outlet dimensions are listed in the product specs and compatible aftermarket tips from vendors like Borla or Magnaflow can be substituted. Contact us to confirm outlet sizing for your specific application.

Stainless steel exhaust systems require minimal maintenance. Periodic cleaning with a stainless steel polish keeps the tips and visible pipe sections looking their best. Inspect the mounting hardware once a season in regions that use road salt in winter months.

Installation Overview

1. Safely lift and support the vehicle to gain access to the full exhaust system
2. Allow the OEM exhaust to cool completely before beginning
3. Apply penetrating oil to all exhaust flange bolts and hangers at least 15 minutes prior to removal
4. Remove the OEM exhaust section by section, starting from the rearmost component
5. Compare the new 49-44125-P sections against the removed OEM pieces to confirm lengths and clocking
6. Hang the new exhaust onto the factory hangers, starting from the front connection point
7. Install all flange bolts and clamps without fully tightening to allow for alignment adjustment
8. Adjust all sections for clearance from body panels, fuel lines, and brake lines
9. Torque all hardware to specification and verify tip alignment before lowering
10. Start the engine and check for exhaust leaks at all joints before the first drive

WARNING: This product can expose you to chemicals including lead and phthalates, which are known to the State of California to cause cancer and reproductive harm. For more information go to www.P65Warnings.ca.gov.