Anyone out there running a K&N filter? How do they stand up to the odd splash of mud & water that enters the air box compared to stock? I'm looking to run one with xr's only slip on muffler unit.Any thoughts on this combo? The bike is a 90 xr600r ,stock motor.I now run a stock exhaust , baffle removed. hoping this pipe will provide more power than present set up & save me an lb. or two in weight. thanks to anyone who can help.