Table of Contents

The Short Answer: Which Diameter Most Owners Should Buy

For most daily-driven trucks running a stock or mild tune, a 4-inch delete pipe is the better fit. It keeps in-cab drone manageable, matches factory-style hanger spacing on most platforms, and moves enough air for stock-to-moderate power levels. A 5-inch pipe earns its place when you are towing heavy, running a higher-horsepower tune, or pairing the pipe with a larger turbo where flow becomes the bottleneck.

Quick Decision Table by Use Case

Use Case Recommended Diameter Why
Daily driver, stock or mild tune 4-inch Lower drone, factory-style fitment
Occasional towing, moderate tune 4-inch or 5-inch Depends on load and tune aggressiveness
Heavy towing, high EGT concerns 5-inch More flow area, lower backpressure under load
Built truck, upgraded turbo, aggressive tune 5-inch Matches higher exhaust volume at high RPM
Show truck or sound-sensitive owner 4-inch Quieter tone, less resonance

What Pipe Diameter Actually Changes

Pipe diameter is not just a cosmetic spec. It changes how the engine breathes after the DPF, cat, and muffler restriction are removed.

Exhaust Flow and Backpressure After the DPF Is Gone

Once the factory DPF and cat are out of the picture, the exhaust gas has a much shorter, more open path to atmosphere. A 4-inch pipe still offers a significant flow improvement over stock, especially on trucks that were never modified beyond the delete. A 5-inch pipe increases the cross-sectional area further, which lowers backpressure at higher exhaust volumes, typically under load, at higher RPM, or with a larger turbo installed. On a stock-power truck, that extra area often goes unused, since the engine simply is not producing enough exhaust volume to fill it.

Think of it this way: the diameter only matters as much as the exhaust volume you are pushing through it. A truck making stock horsepower does not generate enough gas flow to notice much difference between 4-inch and 5-inch. A truck making significantly more power, or one working harder under a heavier load, will notice the extra room a 5-inch pipe provides. This is why the "bigger is always better" mindset does not hold up here. Oversizing the pipe on a mild build mostly adds cost, weight, and drone without a matching gain in flow.

EGTs Under Sustained Load

Exhaust gas temperature climbs fastest when a truck is towing, climbing grades, or running an aggressive tune. Lower backpressure helps the engine push hot exhaust out more efficiently, which can help keep EGTs in a safer range during those sustained-load situations. This is where the 5-inch pipe has a real functional advantage, particularly for owners who tow trailers, haul equipment, or run their truck hard for work. On a truck that mostly sees light commuting, this difference is much smaller and often not noticeable.

Sound Character: Tone, Volume and In-Cab Drone

This is the part most owners actually feel every day. A 4-inch pipe tends to produce a tighter, deeper tone with less low-frequency resonance inside the cab. A 5-inch pipe is louder overall and can introduce more drone at steady highway RPM, especially without a muffler. If you spend a lot of time on long highway trips, the drone from a 5-inch setup is worth test-driving or researching on your specific platform before you commit.

When 4-Inch Is the Better Choice

Stock or Mild Tune, Daily Driving

If your truck is running stock power or a light tune and mostly handles commuting, errands, and light towing, a 4-inch pipe gives you the flow improvement you are looking for without oversizing the system. Most of the flow benefit from removing the DPF and cat happens regardless of whether you choose 4-inch or 5-inch, so a smaller diameter is not leaving meaningful performance on the table for a mild setup.

Keeping Drone Down on Long Highway Trips

Owners who log a lot of interstate miles consistently report less fatigue-inducing drone with a 4-inch system, particularly when a muffler is retained. If in-cab noise at cruising speed is a priority, this is the diameter to start with.

Clearance and Hanger Fitment on Some Cab/Bed Configs

Not every cab and bed configuration has the same amount of room around the factory hanger locations. A 4-inch pipe generally has an easier time matching factory-style hanger points without modification, which matters if you want a straightforward install without custom fabrication. Always check your Vehicle Fit Guide and cab/bed notes before ordering, since exhaust routing can vary across model years and trim levels.

When 5-Inch Makes Sense

Heavy Towing and High EGT Scenarios

If your truck regularly tows near its rated capacity, hauls heavy equipment, or works in demanding conditions, a 5-inch pipe reduces backpressure at the exhaust volumes those situations create. This is a practical, work-focused choice for owners who feel the engine straining under sustained load.

Higher-Horsepower Tunes and Turbo Upgrades

Once you move into aggressive tuning or a larger turbo, the engine is producing more exhaust volume than a stock setup. At that point, a 4-inch pipe can become the flow bottleneck. A 5-inch pipe is sized to keep up with that higher volume so the rest of your build is not held back by the exhaust diameter.

The Tradeoffs: Drone, Cost, Ground Clearance

A 5-inch pipe usually costs more, weighs more, and can sit lower depending on the hanger and routing setup for your platform, which is worth checking if you regularly deal with rough terrain or low clearance situations. Combined with the added drone at highway speed, these are the real tradeoffs to weigh against the flow benefit before you order.

Diameter Availability by Platform

Diameter options and factory-style fitment differ by engine platform. Confirm your exact year, engine, and cab/bed configuration before ordering.

6.7L Powerstroke

Ford 6.7L Powerstroke owners running 2011 to 2019 or 2020 to 2024 trucks can browse 6.7 Powerstroke delete pipes in both diameters. Confirm your year range and Super Duty configuration, since routing and hanger placement shifted across the platform's model years.

6.7L Cummins

Ram 6.7L Cummins owners have both diameters available across the 2007 to 2024 range. Check the 6.7 Cummins delete pipe collection and confirm whether your truck is a standard pickup or Cab & Chassis configuration, since fitment differs between the two.

Duramax LML / L5P

GM Duramax owners on the LML platform (2011 to 2016) or the L5P platform (2017 and newer) each have diameter-specific fitment. Review the L5P Duramax delete pipe or LML Duramax delete pipe options and match the listing to your exact generation, since LML and L5P trucks do not share the same routing.

Do You Need to Change the Tune If You Change Diameter?

Changing pipe diameter alone does not always require a new tune, but pairing a delete pipe with a DPF, EGR, or DEF delete typically does require proper calibration to address check-engine lights and drivability concerns. If you are stepping up to a 5-inch pipe as part of a larger build, this is a good time to review your tuner setup and confirm it matches your intended power level and exhaust configuration. Installing hardware without understanding the tuning requirements can lead to codes or limp mode, so plan the full setup before the first bolt comes off.

Legal Notice: Off-Road and Competition Use Only

Delete pipes and related emissions-system modifications are intended for off-road, race, or non-public-road use where permitted. Do not assume any product is legal for use on public roads with emissions systems disabled. Customers are responsible for confirming compliance with federal, state, and local laws before purchase and installation.

FAQ

Will a 5-inch pipe fit my stock hangers?

In most cases, a 5-inch pipe requires the factory-style hanger location to accommodate the larger diameter, and some platforms handle this better than others. Check the product listing's fitment notes and compatibility warnings for your exact year and cab/bed configuration before ordering.

Can I run 4-inch now and step up later?

Yes. Many owners start with a 4-inch setup on a mild tune and move to 5-inch later if they add a bigger turbo or push into a higher-horsepower tune. Just confirm the new pipe matches your platform and current exhaust routing when you make the switch.

Does diameter affect fuel economy?

Diameter alone is not a reliable predictor of fuel economy change, and EngineGo does not make fuel economy claims without verified data specific to a build. Fitment, tune, driving style, and load all play a bigger role than pipe diameter by itself.

What if I am not sure which diameter matches my hanger setup?

Send your truck's year, make, model, engine, cab style, and bed length to EngineGo support along with photos if your exhaust has already been modified. A quick fitment check before ordering is faster and cheaper than dealing with a return on an installed part.

Still not sure which diameter fits your exact truck? Shop delete pipes by platform and diameter or send your year, make, model, and engine to EngineGo support for a fitment check before you order.