The Zephyr-χ compatible version of RPM's full exhaust series "RPM-4in2in1" has gotten a revamp. This series has been popular since its launch in 1978 and as the name suggests, it features a 4-2-1 pipe and merge collector layout.
Table of Contents
RPM's full exhaust series "RPM-4in2in1" revamped for Zephyr-χ

The Zephyr-χ has been out of production for nearly 20 years, and as the number of used bikes on the market has decreased, the number of compatible full exhausts (up to the 2008 final model year) that are certified to meet Japan's public road standards has been decreasing year by year. Currently, only three companies: Moriwaki Engineering, Yamamoto Racing, and Nojima Engineering offer them. With this decrease in options, RPM has newly acquired JMCA certification for their Zephyr-χ full exhaust in 2025.
Specifications
In order for the exhaust to be certified, some specifications were revised: a new catalytic converter is built into the exhaust pipe, while retaining the company's commitment to the 4-2-1 exhaust pipe layout and slim silencer (67mm O.D., 300mm overall length).




[RPM Exhaust Sound] Kawasaki ZEPHYR400χ [2001-2008] RPM-4in2in1 Exhaust
Product Lineup
The silencer cover will be offered in the same three versions as before the revamp: Aluminum, Stainless Steel, and Titanium.

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