20-01-16, 11:13 PM
The ad says no rejetting required, which isn't quite the same thing. 
The FZS1000 is sensitive to exhaust header design. If the primary and secondary pipe lengths on a 4-2-1 system aren't right, you get a flat spot in the 3 - 4k rpm range which is impossible to tune out. I've seen dyno charts for these headers and it's clear that they're not as well designed as the systems offered by Akrapovic and the other recognised exhaust specialists.
Get the EXUP working properly rather than wire it open.
The FZS1000 is sensitive to exhaust header design. If the primary and secondary pipe lengths on a 4-2-1 system aren't right, you get a flat spot in the 3 - 4k rpm range which is impossible to tune out. I've seen dyno charts for these headers and it's clear that they're not as well designed as the systems offered by Akrapovic and the other recognised exhaust specialists.
Get the EXUP working properly rather than wire it open.