One of the most common enquiries we receive regarding our generator exhaust extension kits is:
“Can I add a second muffler or silencer to make my generator quieter?”
The answer is: yes, sometimes - but not always in the way people expect.
Many generator owners assume that if a genset is noisy, the exhaust must be the cause. In reality, the exhaust is often only one contributor to the overall noise output. Before investing in a secondary silencer, it’s important to understand where the noise is actually coming from.
Understanding Generator Noise Sources
A generator produces noise from several different sources, including:
- Exhaust gas exiting the engine
- Engine mechanical noise
- Cooling fans and airflow
- Alternator noise
- Belts and pulleys
- Vibrations transmitted through the frame or mounting surface
- Acoustic reflections from nearby buildings, walls, containers or enclosures
Industry references consistently identify the engine casing, cooling system and exhaust as separate noise sources that must be evaluated independently. Simply treating one source may not achieve the desired result if another source is dominant.
This is why two generators with identical engines can sound completely different depending on their installation environment.
The First Question: How Loud Is It?
Before recommending any silencer upgrade, we typically ask:
- Is the generator already fitted with an acoustic enclosure?
- Does it already have a factory-fitted muffler?
- What are the current sound levels?
- Where are the noise complaints being received?
- What is the distance between the generator and the affected area?
Without this information, selecting a secondary silencer is largely guesswork.
A few simple dB(A) readings can provide valuable insight into whether the exhaust is actually the dominant noise source.
Why Exhaust Extensions Often Help More Than Expected
Many customers are surprised to learn that extending the exhaust can sometimes provide a greater benefit than adding another muffler.
By extending the exhaust:
- The discharge point can be moved further away from occupied areas.
- Noise can be directed upward instead of horizontally.
- Exhaust noise can be discharged above fences, walls or structures.
- Sound reflections can be reduced.
In many situations, simply relocating the exhaust outlet is enough to bring perceived noise levels back within acceptable limits.
This is one of the reasons our generator exhaust extension kits are so popular. Often, the issue isn’t how much noise is being generated - it’s where that noise is being directed.
Remember though, to always choose an appropriately sized exhaust extension for your generator - we can help you determine if backpressure is a concern.
Have a look at our off-the-shelf generator exhaust extension kits here.
The Truth About Secondary Silencers
Secondary silencers can absolutely work when properly designed and selected.
The problem is that many people expect dramatic reductions simply by installing an additional muffler into the exhaust line.
Unfortunately, that’s rarely how it works.
A poorly selected secondary silencer may:
- Provide little measurable noise reduction
- Target the wrong frequency range
- Create unnecessary exhaust restriction
- Increase engine backpressure
- Reduce engine performance
- Increase fuel consumption
- Contribute to overheating issues
Generator silencers are engineered devices that must be selected based on:
- Engine size and exhaust flow
- Exhaust temperature
- Existing silencer performance
- Desired attenuation level
- Available backpressure allowance
A silencer that reduces noise but exceeds the manufacturer’s maximum backpressure limits can create more problems than it solves.
What Sort of Noise Reduction Can You Expect?
For generators that are already fitted with a factory muffler and acoustic enclosure, a secondary silencer often provides relatively modest reductions in overall sound levels.
In our experience, additional reductions of approximately 5–7 dB(A) are common when retrofitting a secondary silencer to an already silenced generator.
However, this figure can vary significantly depending on:
- Generator design
- Existing silencer specification
- Exhaust layout
- Installation environment
- Dominant noise frequencies
It’s important to remember that a 5 dB(A) reduction can still represent a noticeable improvement to the human ear, particularly when targeting specific objectionable frequencies.
When Secondary Silencers Make Sense
A secondary silencer is often worthwhile when:
- Exhaust noise has been confirmed as the dominant source.
- Noise complaints relate to tonal or frequency-specific exhaust noise.
- The existing silencer is industrial-grade and additional attenuation is required.
- An exhaust extension is already being installed.
- Backpressure calculations confirm sufficient capacity exists.
In these cases, an absorptive or combination-style silencer may help target the frequencies that are causing the greatest annoyance. Reactive, absorptive and combination silencers all perform differently depending on the noise spectrum being addressed.
The Importance of Backpressure
Every engine manufacturer specifies a maximum allowable exhaust backpressure.
This limit exists because excessive restriction can negatively affect:
- Engine performance
- Fuel consumption
- Exhaust gas temperatures
- Turbocharger operation
- Engine durability
Before any secondary silencer is installed, the available backpressure allowance should be assessed.
This is particularly important on smaller generators, where there is often less margin available.
Our Recommendation
If you’re considering a secondary silencer, start by identifying the actual source of the noise.
We generally recommend:
- Measuring existing sound levels.
- Determining whether the noise is predominantly exhaust-related.
- Considering an appropriately sized exhaust extension and outlet relocation.
- Assessing available backpressure allowance.
- Selecting a secondary silencer specifically designed for the engine and application.
A properly engineered secondary silencer can certainly help.
Simply installing “another muffler” because the generator seems noisy often won’t.
Need Advice?
At Ultimax Industries, we regularly assist customers with generator exhaust extensions, silencer selection, backpressure assessments and noise reduction strategies.
If you’re experiencing noise issues, contact our team with:
- Generator make and model
- Existing exhaust configuration including diameters and lengths
- Approximate sound levels (if known)
- Photos of the installation
We’ll help determine whether a secondary silencer is likely to provide a worthwhile improvement, or whether a different approach may deliver better results.