A Bark Box is a high-performance muffler cover made by Westcoast Saw for select Stihl chainsaws with two-piece mufflers. It increases exhaust airflow to boost power, improve torque, run cooler, and produce a louder, distinct sound compared to a stock muffler.
What is a Bark Box on a Chainsaw?
The Bark Box is an aftermarket muffler cover designed to replace the stock front piece on certain chainsaw models. Made by Westcoast Saw, this modification took over a year to perfect through extensive testing and development. Unlike other muffler mods that simply open existing ports, the Bark Box creates an entirely new exhaust pathway.
How it differs from a stock muffler
A stock chainsaw muffler is typically restrictive by design, primarily to meet noise regulations that prevent manufacturers from producing overly loud machines. In contrast, the Bark Box is constructed of 304 stainless steel and hand TIG welded, offering substantially larger exhaust outlets.
This modification differs from stock mufflers in three key ways:
- It creates an alternative route for exhaust gasses to exit the engine
- It includes a built-in spark arrestor with a screen size of 0.021
- It maintains the original rear muffler outlet while adding front exhaust pathways
The result? Engine temperatures drop noticeably, and most users report a 6-10% horsepower gain throughout the RPM range. Additionally, for non-M-tronic saws, retuning is recommended after installation, while M-tronic models will self-tune by the third or fourth cut.
Why it’s called a ‘Bark Box’
The name “Bark Box” precisely describes what you’re getting – a muffler that makes your saw “bark”. Owners consistently describe the sound as “rowdy” and dramatically different from stock exhaust notes. One user noted that “every stroke of the piston created a percussion you could feel in your chest”.
The sound is so distinctive that Westcoast Saw incorporated it directly into the product name, letting customers know exactly what to expect – a saw that announces its presence with authority.
Common models it’s used on (e.g., Stihl 500i)
Bark Boxes are compatible only with chainsaws featuring two-piece muffler covers. They’re especially popular on professional-grade Stihl models, including:
- MS500i (one of the most popular applications)
- MS362/MS400
- MS461/460/046/440/044
- MS660/066
- MS661
- MS880/881
- MS462
- 034/036/360
- 084
The modification has become particularly sought-after among professional loggers and chainsaw enthusiasts looking for both performance gains and the distinctive sound profile.
Performance Benefits of a Bark Box
Installing a Bark Box on your chainsaw delivers several measurable performance improvements that go beyond just sound. Let’s explore the practical benefits this modification provides to your cutting machine.
Increased exhaust flow and power
The primary advantage of the Bark Box is the noticeable power gain it delivers. By creating an alternative route for exhaust gasses, the engine can run more efficiently, producing 6-10% more horsepower throughout the RPM range. This power increase isn’t just marketing hype—it’s confirmed by numerous users who report their saws “bite through hardwood” more aggressively after installation. Moreover, the improved airflow allows the engine to achieve more revolutions per given time, resulting in better torque and cutting performance.
Sound output and tone changes
Once installed, the sound transformation is dramatic. The Bark Box earns its name by producing what many describe as a “rowdy” exhaust note. One user stated their saw “screamed like a banshee when new; everyone this side of the county knew when I fired up to cut”. Consequently, hearing protection becomes even more essential, as the percussion created is intense enough to be physically felt in your chest.
Reduced back pressure and heat buildup
Perhaps the most significant long-term benefit is temperature management. The Bark Box consistently reduces engine operating temperatures. This cooler operation occurs because the additional exhaust pathway allows heat to exit the system more efficiently. As a result, many professional users install Bark Boxes on high-performance saws like the Stihl 500i specifically to reduce overheating during extended use.
Impact on fuel tuning and carb adjustments
The improved exhaust flow necessitates fuel adjustments to maintain proper air-fuel mixture. For M-tronic models, the saw will self-adjust within “the third or fourth cut after installation”. However, non M-tronic saws require manual carburetor adjustments—typically 1⅛ to 1¼ turn on the low screw and 1 to 1⅛ turn on the high screw at sea level. Without proper tuning, the saw might run lean, potentially causing overheating and engine damage.
Real-World Results from Users
Opinions about the bark box chainsaw muffler vary widely among real-world users, ranging from enthusiastic endorsements to skeptical criticism. Let’s examine what actual users have discovered after installing this modification.
Feedback from professional loggers
Professional timber fallers remain divided on what is the purpose of a bark box on a chainsaw. Several commercial loggers use them primarily for heat management rather than power gains. Notably, many professionals must switch to non-modified mufflers during fire season or when working on federal lands. Among those who endorse bark boxes, many cite that these modifications help saws maintain lower operating temperatures. Nevertheless, some logging contracts explicitly ban saw modifications, creating a gap in reliable professional data.
Casual user experiences
Weekend warriors often report mixed results with the bark box muffler. One user described their experience: “Every stroke of the piston created a percussion you could feel in your chest”. Another mentioned their Stihl saw “turned into a sports car with the bark box”. On the other hand, many casual users acknowledge the extreme noise levels, noting that “ear plugs alone were not enough”. First-time users frequently comment that the sound is initially overwhelming but eventually “mellows out” after extended use.
Dyno test results and power gains
Independent testing suggests more modest benefits than marketing claims. One dyno test comparing a ported MS661 with different configurations found:
- Stock muffler with Bark Box cover: Temperature increased by 15.3°F
- 7% performance gain on a Stihl MS500i
Bar and chain setups that pair well
Users report that bark box chainsaws work best with specific configurations. For instance, the 36″ bar with full comp chain typically requires careful management to prevent overheating. For the MS661 with a bark box, many prefer running 28″ and 32″ bars on full comp chains with depth gages set to .050″. Alternatively, some operators recommend 32″ with a full skip chain for optimal performance.
Is a Bark Box Right for You?
Deciding whether to invest in a bark box chainsaw muffler depends primarily on your specific cutting needs and operating environment. Let’s examine if this modification aligns with your requirements.
When it’s worth the investment
Professional timber fallers typically benefit most from what is a bark box on a chainsaw. For felling operations where saws run hard briefly then cool down, the performance gain justifies the expense. Casual users may find the cost harder to justify unless they regularly cut hardwoods. The bark box particularly benefits those using longer bars (28-32″) who need additional power to maintain cutting speed.
Fire season and legal considerations
Throughout fire season or when working on federal government lands, modified mufflers often face strict regulations. Most jurisdictions require spark arrestors during dry conditions to prevent wildfires. Fortunately, quality bark box mufflers include built-in spark arrestor screens (0.021 size) for compliance.
Swapping covers for compliance
The ability to quickly switch between stock and modified covers represents a key advantage for professional users. This feature allows loggers to maintain legal compliance by simply changing covers rather than entire muffler assemblies when moving between regulated and unregulated cutting zones.
Alternatives like dual-port mufflers
Dual-port mufflers offer a middle ground between stock and bark box performance. According to some experts, they provide modest gains while producing less noise. These typically cost less than bark boxes yet still improve exhaust flow over stock configurations.
Conclusion
After examining all aspects of the bark box chainsaw modification, we can see why this upgrade generates such enthusiasm among serious saw operators. The combination of improved performance, reduced operating temperatures, and that unmistakable aggressive sound creates a compelling package for many users. Additionally, the 6-10% power gain throughout the RPM range makes a noticeable difference when cutting through hardwoods or using longer bars.
However, this modification certainly isn’t for everyone. The extreme noise levels demand serious hearing protection, and legal restrictions during fire season might require you to swap back to stock components. Furthermore, casual users might question whether the performance benefits justify the investment for occasional cutting tasks.
The bark box ultimately represents a specialized tool for those who demand maximum performance from their chainsaws. Professional timber fallers generally appreciate these benefits most, particularly when running professional-grade Stihl models like the popular 500i. For weekend warriors, the decision comes down to how frequently you use your saw and whether you value that distinctive, chest-thumping bark that announces your presence across the forest.
