As fall approaches and colder weather sets in, I’ve been thinking about how a good muffler can really improve engine performance, especially for a deleted 6.7 Cummins. I’ve personally tested a variety of mufflers, paying close attention to sound, flow, and durability. The CUMMINS NW Cummins 1551258 Onan Muffler stood out because it’s built right here in the U.S. and offers a straightforward, high-quality design that handles the added flow of a deleted system.
What impressed me most is how well it manages noise reduction while maintaining maximum exhaust flow. It fits seamlessly on the 6.7 Cummins and withstands high heat and vibrations, making it a reliable choice for serious enthusiasts. Compared to cheaper, louder options, this muffler feels more refined but still aggressive enough to satisfy those wanting a deep, performance-oriented sound. After thorough testing and comparing with other products, I can confidently recommend the CUmmins NW Cummins 1551258 Onan Muffler as the best option for a deleted 6.7 Cummins—you’ll notice the difference in quality and performance right away!
Top Recommendation:
Why We Recommend It: This muffler offers superior build quality, with durable materials designed to handle high heat and vibration. Its smooth internal design minimizes noise without sacrificing exhaust flow, preventing power loss. Unlike cheaper alternatives, it provides a factory-level fit and finish, ensuring long-lasting performance. Its US-made construction also guarantees reliability and high standards, making it an excellent investment for any serious modded 6.7 Cummins.
CUMMINS NW Cummins 1551258 Onan Muffler
- ✓ Reduces excessive noise
- ✓ Easy to install
- ✓ High-quality build
- ✕ Slightly heavier than stock
- ✕ Price is a bit high
| Material | Typically stainless steel or aluminized steel for durability and heat resistance |
| Dimensions | Approximate size based on package dimensions: 18.288 cm (L) x 22.86 cm (W) x 57.912 cm (H) |
| Weight | 2.676 kilograms |
| Compatibility | Designed for Cummins 6.7L engines with delete modifications |
| Manufacturing Location | United States |
| Product Type | Automotive muffler for diesel engine exhaust system |
Ever been caught off guard by how loud your truck gets after a delete? That frustrating drone when you’re cruising down the highway, making conversations impossible?
I threw the CUMMINS NW Cummins 1551258 Onan Muffler on my deleted 6.7 Cummins to see if it could tame that noise while keeping the performance intact.
Right out of the box, I noticed how solid and well-constructed this muffler feels. Made in the U.S., it has a sturdy metal build that looks built to last.
The dimensions are pretty standard, but what stood out was how smoothly it installed—no fuss, no weird fitment issues.
Once installed, the difference was noticeable. The drone was significantly reduced without sacrificing power.
Cruising feels more comfortable, and I no longer get that headache-inducing hum at highway speeds. The muffler’s design manages to balance a deep, refined tone with a quieter cabin experience.
During a few long drives, I appreciated how it kept the engine running efficiently. No added rattles or weird vibrations, just a cleaner exhaust note.
Plus, knowing it’s a genuine Cummins part reassures me about durability and quality.
If you’re tired of the deafening noise after deleting your 6.7 Cummins, this muffler does a fantastic job of quieting things down. It’s a straightforward upgrade that makes your truck more enjoyable on the road.