aFe Large Bore-HD Cat-Back Exhaust System

2003–2004 Dodge Ram 2500 / Ram 3500 5.9L Cummins

Part #: 49-12005

Overview

The aFe Large Bore-HD Cat-Back Exhaust System is a precision-engineered performance upgrade designed specifically for 2003 and 2004 Dodge Ram 2500 and Ram 3500 trucks equipped with the 5.9L Cummins engine. This system replaces the restrictive factory exhaust with a mandrel-bent, aluminized steel design that enhances exhaust flow, resulting in improved horsepower, torque, and overall engine efficiency. Built to withstand the rigors of heavy-duty use, it is an ideal solution for Ram owners who regularly tow or haul and demand both durability and performance.

Beyond performance gains, this exhaust system delivers a bold, aggressive exhaust tone that enhances the driving experience without compromising reliability or factory fitment. Its direct bolt-on design ensures an easy installation process, making it a practical upgrade for enthusiasts and professionals alike.

Key Features

Engineered with premium materials and advanced design techniques, the aFe Large Bore-HD Cat-Back Exhaust System offers a range of features that maximize performance and durability:

• 4-inch mandrel-bent aluminized steel tubing for smooth, unrestricted exhaust flow
• High-flow, straight-through perforated muffler (8" diameter x 30" length) delivering aggressive sound with minimal backpressure
• Optional straight muffler delete pipe for maximum exhaust flow and a louder, more pronounced exhaust note
• Bayonet-style hangers with swaged ends for secure, rattle-free mounting
• Slotted and swedged pipe ends paired with premium band clamps ensure a tight, leak-free seal
• Increases exhaust flow by up to 29% and reduces exhaust gas temperatures by up to 100°F
• Constructed from durable 409 stainless steel for corrosion resistance and long service life
• Maintains factory mounting points and includes a 2-piece tailpipe for easy adjustment and alignment
• Tested on flow benches and dynamometers to optimize pipe diameter and muffler design
• Backed by a 2-year limited warranty for peace of mind

Construction & Design

This cat-back exhaust system is crafted from premium 409 stainless steel, chosen for its excellent corrosion resistance and ability to withstand harsh operating conditions typical of heavy-duty trucks. The exhaust tubing is mandrel bent to maintain a consistent 4-inch diameter throughout the system, eliminating flow restrictions caused by sharp bends and improving exhaust gas velocity.

All pipe ends are slotted and swedged to ensure secure, leak-free connections when combined with the included high-quality band clamps. The fully welded bayonet-style hangers with swaged ends lock the system firmly in place while utilizing factory mounting points, allowing for a straightforward installation without modifications.

Performance & Sound

Designed to enhance both performance and auditory experience, the aFe Large Bore-HD Cat-Back Exhaust System increases exhaust flow by up to 29%, contributing to noticeable improvements in horsepower and torque. It also reduces exhaust gas temperatures by as much as 100°F, helping maintain optimal engine operating conditions during heavy towing or hauling.

The included straight-through perforated muffler produces an aggressive, deep exhaust tone that complements the power gains without excessive drone. For those seeking an even louder and more aggressive sound, the system offers a straight muffler delete pipe option, allowing customization of exhaust volume and flow to personal preference.

Installation & Fitment

This exhaust system is designed for a direct bolt-on installation on 2003 and 2004 Dodge Ram 2500 and Ram 3500 trucks equipped with the 5.9L Cummins engine. It uses all factory mounting points and includes detailed installation instructions, premium band clamps, and fully welded hangers to ensure a secure and leak-free fit.

The two-piece tailpipe design allows for easy adjustment to achieve proper alignment and clearance without the need for cutting or welding. This makes the system accessible for experienced DIY installers as well as professional shops.

What's Included

• 4-inch mandrel-bent aluminized steel exhaust tubing
• 8" diameter x 30" length straight-through perforated muffler
• Straight muffler delete pipe
• Premium band clamps for secure connections
• Fully welded bayonet-style hangers
• 2-piece adjustable tailpipe
• Detailed installation instructions

Ideal For

This exhaust system is ideal for Dodge Ram 2500 and Ram 3500 owners from model years 2003 to 2004 who seek enhanced engine performance, improved exhaust sound, and increased durability. It is especially suited for heavy-duty truck users who regularly tow or haul and want to reduce exhaust gas temperatures while gaining horsepower and torque. Enthusiasts looking for a bold, aggressive exhaust note without sacrificing reliability will also appreciate this upgrade.

aFe POWER (Advanced FLOW Engineering) offers dyno-proven intake, filtration, and exhaust upgrades aimed at measurable performance gains. The brand’s lineup is geared toward enthusiasts looking for better airflow, improved sound, and durable materials—from cold air intakes to stainless exhaust systems for street and track applications.