Engineered for the CRF 300L Yoshimura RS4 muffler, this quiet insert delivers measurable noise reduction without sacrificing performance. Compatible with or without the Yoshimura spark arrestor, it achieves approximately a 6dB reduction at idle and 5500RPM—translating to roughly 30% perceived sound pressure reduction. Due to the logarithmic nature of the decibel scale, this modest technical decrease produces a substantially quieter riding experience. The insert maintains the system's power delivery while making it significantly more refined and street-friendly.
