Undaunted Mfg MS261 Full Exhaust

Engineered for increased power and improved engine cooling, this high-performance exhaust system is precision CNC machined from 6061-T6 billet aluminum, a high-strength, aerospace-grade alloy known for excellent heat dissipation and durability. Built for demanding conditions and proudly made in the USA.

Compatible Models:

STIHL MS 261 / MS 261 C / MS 261 C-M (M-Tronic Version 3.0+ only)

Important: Not compatible with M-Tronic Version 2.0 or earlier due to limited fuel adjustment capabilities. Carbureted models are fully compatible.

How to Check Your M-Tronic Version:

Version 3.0+ saws are typically manufactured in 2019 or later. Verify the control module part number or consult a STIHL dealer to confirm compatibility.

Outlet Direction (Facing Bar or Facing Recoil):

Facing Bar means the exhaust outlet points toward the guide bar side of the saw. Facing Recoil means it points toward the pull-start side. This is strictly operator preference and has no effect on performance.

What's Included:

Billet exhaust base, one-piece exhaust cover, high-temperature gasket (between cover and base), spark arrestor screen with aperture size compliant with USFS specifications, complete hardware kit, and Loctite 243 Threadlocker (0.5 ml bottle).

Dyno Proven Performance:

Tested on a completely stock saw with no modifications other than the exhaust. Results showed a 13.70% increase in horsepower and a 12.30% increase in torque.

Performance gains will vary depending on the saw and the level of modification.

Installation Notes:

• Post-installation tuning or recalibration is required for optimal performance. Follow the appropriate STIHL M-Tronic calibration procedure for equipped models.

• Apply the supplied threadlocker to all mounting screws and torque to the values specified in the installation instructions. Retorque after the first few heat cycles and periodically check torque as part of routine maintenance.

Exhaust Sound:

Increased exhaust noise is expected compared to the factory exhaust. Proper hearing protection is essential and should always be worn.