Yoshimura Straight Cyclone for Kawasaki Z1 and Z2 is one of their long seller in their lineup.

The Yoshimura traditional style 4-1 system is the best match for these bikes.

[Webike Japan Product Page]
Machine Bent Straight Cyclone

•Description
Main Material: Steel
JMCA Approved No.: 00129079
Static Noise Decibel: dB/Measured at : rpm 93dB/4250rpm

•Contents
M6 & M8 Stud bolts

Original Source[ YOSHIMURA JAPAN FACEBOOK ]

See Accessories of Yoshimura
See Kawasaki Moto Index Page
See Accessories for KAWASAKI Z1
See Accessories for KAWASAKI Z2