You NEED a filter on the there dude
not so sir. when you capitalized "need" one could deduce you are saying "mandatory" or "required". that just isn't the case. each rocker box lid contains a breather check-valve assembly which is a one-way petal valve and to which the breather line attaches. crankcase pressurized air only comes out...it cannot flow into the motor via the valve. i've installed probably 30 buell breather re-route systems and makes no difference if a breather is attached to end of your new hose line or not. if you feel that a small breather enhances the appearance or makes you feel better about the task then please attach one. same goes for "puke bottle". if your XB motor is in sound condition with no internal problems you should have few if any liquids flowing out the breather ports.