Hi, I just bought a slip on and a k&n air filter, do i need to rejet my bike before installing these? thanks

 

Usually you do need to rejet carbs with new exhaust...There are a few makers that don't require rejetting...Aftermarket mufflers have better flow...along with a less restrictive air filter, you are now moving MUCH more air, in turn, you need MUCH more fuel, otherwise you will be running a lean mixture which generates alot more heat...NOT GOOD! You may start melting pistons if ran under theese conditions...

 

+1 with FNQuick...with just a slip-on you may run fine, but with a slip-on and a K&N...probably would need rejetting...at least to get the most out of the increased airflow.