I bought my friends 2007 400ex and he has a Carbon fiber HMF bill ballance slip on pipe on it. does it need to be rejetted because he didn't and i don't want it to mess anything up.

 

yes

any other mods

 

I ended up not buying it because the frame had some rust. Clutch wasnt working properly, tail light cover was busted. The exhaust was clearly affected by not having it jetted properly because it was popping bad and even blew flames once. So I'm gonna try to find something else. I want a good looking decently good conditioned 400 that is reliable for 2,000.