If it's just the endcan, like a slipon, then is does not NEED to be, but you'll probobly get some more performance if you do.
See how it runs, ride around for a bit. If the engine feels weird, then get it jetted
If it was a full system, you DO NEED to get it jetted.
Also if you got just the endcan and also put a K&N Airfilter in, a rejet is a very good idea...
-=Welcome To Canada=-
2002 Green 6R
1986 Gixxer 7/11
See how it runs, ride around for a bit. If the engine feels weird, then get it jetted
If it was a full system, you DO NEED to get it jetted.
Also if you got just the endcan and also put a K&N Airfilter in, a rejet is a very good idea...
-=Welcome To Canada=-

2002 Green 6R
1986 Gixxer 7/11