In the realm of diesel vehicle performance modifications, upgrading the exhaust system is a crucial step to enhance power, improve exhaust sound, and optimize fuel efficiency. This is especially true for turbocharged models like the Dodge 6.7L Cummins.
This article delves into the definition of Turbo Back Exhaust systems, their differences from Cat Back Exhausts, and their roles in DPF Delete applications, guiding you to make informed modification choices.
What is a Turbo Back Exhaust System and What Does It Include?
In the diesel engine world—especially for heavy-duty pickups like the Ford 6.7 Powerstroke—a Turbo Back Exhaust system refers to a complete exhaust upgrade starting from the turbocharger outlet all the way to the tailpipe. This system typically includes the downpipe, DPF section, catalytic converter (CAT), mid-pipe, and cat-back exhaust.
Compared to a Cat Back system, which only upgrades the rear portion of the exhaust, a Turbo Back is far more comprehensive. It significantly improves airflow, reduces backpressure, and unlocks engine performance otherwise restricted by stock emission components. According to 2024 data from SEMA (Specialty Equipment Market Association), a full exhaust upgrade can increase horsepower by up to 18–25 HP, especially when combined with a DPF delete and ECU tuning.
Additionally, because the Turbo Back system affects the entire exhaust path, it directly impacts turbo responsiveness. Many users report noticeably quicker throttle response and smoother acceleration—particularly during towing or hill climbing—after installing a Turbo Back system.
Key Performance Benefits of a Turbo Back Exhaust
One of the biggest benefits of choosing a Turbo Back Exhaust system is the noticeable leap in performance—especially when paired with a DPF delete and ECU retune. According to a 2023 test by Diesel World Magazine, a 2017 Ford F-250 6.7 Powerstroke equipped with a SPELAB 5" Turbo Back system showed gains of 22 horsepower and 38 lb-ft of torque solely from the exhaust upgrade. Here are the key advantages:
Reduced Exhaust Backpressure
In turbocharged engines, high backpressure under load hinders performance. A Turbo Back system eliminates factory restrictions like the DPF and CAT, allowing gases to exit freely and improving engine output.
Improved Turbo Spool-Up Time
Especially at lower RPMs, the turbo can “wake up” faster, reducing turbo lag and providing smoother, more responsive acceleration.
Better Fuel Economy
Enhanced airflow leads to more efficient combustion. Real-world tests show fuel savings of 5% to 10% in city driving.
Deeper, More Aggressive Exhaust Note
While not everyone’s priority, diesel enthusiasts often appreciate the richer, throatier exhaust tone that a Turbo Back system delivers.
Turbo Back vs. Cat Back vs. Downpipe Back: System Comparison
Understanding the structural differences between exhaust systems is essential to choosing the right upgrade. The major distinction between Turbo Back, Cat Back, and Downpipe Back systems lies in where they start replacing the exhaust piping and whether they can support a DPF delete.
Let’s take the 2020 Ford F-350 6.7L Powerstroke as an example to explore how each system performs:
1. Turbo Back Exhaust: The Maximum Performance Path
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Replaces the entire exhaust system from the turbo outlet to the tailpipe, including the downpipe, DPF section, CAT, mid-pipe, and rear section;
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Offers the most complete airflow optimization, fully supports DPF delete;
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Cons: Complex installation, requires ECU tuning, and is not legal for street use unless off-road;
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Best for: Power-focused users, towing, off-roaders, or track-only builds.
2. Downpipe Back Exhaust: Moderate Upgrade with Modular Flexibility
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Starts after the downpipe, does not include the DPF section;
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Can be paired with a DPF delete downpipe to create a full DPF delete setup;
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Easier to install, more budget-friendly than a full turbo back;
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Best for: Users seeking a cost-effective upgrade with DPF delete potential.
3. Cat Back Exhaust: Entry-Level Sound and Aesthetic Upgrade
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Replaces piping after the DPF or CAT, leaving the front system intact;
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Cannot support DPF delete, as it doesn’t touch emission-critical components;
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Easiest to install, requires no tuning and won’t trigger check engine lights (CEL);
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Best for: Daily drivers looking for improved sound and style without emission concerns.
The Relationship Between Cat Back and DPF Delete: Compatible or Conflicting?
Many diesel truck owners often mistakenly believe that installing a Cat Back Exhaust system equates to performing a DPF Delete. In reality, Cat Back systems do not directly remove the DPF, but under certain conditions, they can function as a supporting component for a DPF-deleted setup.
Let’s take a 2018 Ram 2500 6.7L Cummins as an example:
Cat Back Does Not Equal DPF Delete
The Cat Back system starts after the catalytic converter or diesel particulate filter (DPF). It does not interact with or modify the emissions components, making it a safer choice legally—but also incapable of removing or bypassing the DPF. If your goal is to eliminate the DPF for more power or fewer regen cycles, a Cat Back alone won’t do the job.
Cat Back Can Complement a DPF-Deleted Setup
On vehicles where the DPF has already been removed via a Turbo Back or Delete Downpipe, a high-flow Cat Back system can serve as a rear-stage performance enhancer, improving exhaust tone and ensuring smooth airflow. SPELAB’s performance Cat Back units, for example, are engineered to pair seamlessly with front-end deletes for optimal results.
Practical Tip: How to Combine It
If you aim for a complete DPF Delete in one go, a Turbo Back system is the best option. However, if you’re modifying in stages due to budget or installation constraints, you can start with the downpipe and mid-pipe delete, and add a Cat Back system later as the final upgrade.
Are Turbo Back Exhaust Illegal?
For most diesel truck owners, the biggest appeal of a Turbo Back Exhaust system is the dramatic increase in power—especially when combined with a DPF delete. However, it’s also one of the riskiest modifications from a legal standpoint. The U.S. Environmental Protection Agency (EPA) and California Air Resources Board (CARB) enforce strict rules regarding emissions equipment, and understanding those regulations is essential.
Current U.S. Legal Landscape
According to EPA regulations, removing or bypassing emissions devices such as the DPF or CAT on any road-legal vehicle is illegal. This means:
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Installing a Turbo Back system (if it deletes the DPF) = illegal for street use;
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In states like California, even replacing factory exhaust components without CARB approval can be a violation.
As of a 2023 EPA report, over 11,000 diesel vehicles were flagged in 2022 for illegal emissions modifications. Some owners and shops were fined tens of thousands of dollars.
Legal Use: Off-road Only
Many manufacturers—including SPELAB—clearly label their Turbo Back or DPF Delete kits as “For Off-road or Competition Use Only.” These systems are intended for off-road, towing, or closed-track environments, not public roads.
For instance, if you own a 2019 Ford F-250 used for trail work or farm towing on private property, using a Turbo Back system is a legitimate upgrade. But if you daily drive that same truck in the city, you risk legal penalties and failed emissions inspections.
Compliance Tips
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If legality is a concern, consider high-flow DPF systems combined with ECU tuning as an alternative;
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Choose CARB-approved Cat Back systems to improve performance and sound without removing emissions components;
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Always ensure that any DPF delete product is kept off public roads and retain your OEM parts for future restoration.
Recommended Product: SPELAB 6.7 Cummins 5-Inch Turbo Back Exhaust
Among the many Turbo Back exhaust options, the SPELAB 5-Inch Turbo Back Exhaust Kit—built for 6.7L Cummins engines in Ram 2500 and 3500 trucks—stands out with its full-system design, robust flow improvement, and long-term reliability. It’s particularly suited for Ram models from 2010 to 2023 equipped with the legendary Cummins diesel platform.
Product Highlights
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Complete System Coverage: Replaces everything from the turbo outlet to the tailpipe, designed to fit OEM turbo flanges;
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5-Inch Oversized Tubing: Delivers smoother flow, reducing backpressure by up to 50%, lowering exhaust temps and increasing torque;
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DPF Delete Compatible: Works perfectly with SPELAB delete downpipes and race tuners for maximum off-road performance;
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304 Stainless Steel Construction: Built to handle corrosive, high-heat, high-load conditions in real-world usage;
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Available in Straight-Pipe or Muffled Versions: Match your exhaust tone preferences with either raw or refined sound options.
Field-Tested Results
In a February 2024 test by “SPELAB” on a 2021 Ram 3500, the system showed:
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+21.7 HP gain
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+34 lb-ft torque increase
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Exhaust gas temperature drop of 46°C
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Fuel economy improved by ~7%
These benefits make it an ideal upgrade for hauling 5th wheel trailers, worksite gear, or going off-grid where Cummins power matters most.
Share Your Experience and Inspire the Diesel Community
Every exhaust upgrade is more than a power boost—it’s a reflection of the driver’s personality and journey. Have you completed a DPF delete? Did your turbo spool faster after installing a Turbo Back system? What made you choose SPELAB? Your real-world experience can help fellow diesel enthusiasts and fuel the passion of our entire community.
FAQ
Q1: Do I need to retune my engine after installing a Turbo Back Exhaust?
A1:Yes—especially if the system removes the DPF or catalytic converters, ECU remapping or tuning is essential. It prevents check engine lights (CEL) and ensures that turbo boost, fuel delivery, and other parameters align with the new airflow characteristics for safe and optimal performance.
Q2: Will a Turbo Back Exhaust void my factory warranty?
A2: In most cases, if the Turbo Back system causes engine issues or emission non-compliance, the manufacturer may deny warranty claims related to those parts. It’s wise to retain your OEM components and verify your vehicle’s condition before modification. Off-road or competition-only vehicles typically fall outside factory warranty coverage.
Q3: Does SPELAB offer muffled versions of its exhaust systems?
A3: Yes—SPELAB offers both straight-pipe and muffled versions of its exhaust systems. Users who prefer a deeper, more refined tone may opt for the muffler version, while those aiming for maximum airflow often choose the straight-pipe configuration.
Q4: Can I revert to the stock exhaust before inspection?
A4: Yes. If you’ve kept your factory exhaust system, most Turbo Back or DPF Delete setups can be reversed relatively quickly, though some mechanical skill or professional help may be needed. SPELAB’s flange and clamp design makes disassembly easier for inspection or temporary compliance.
