My 09 1700 Nomad has this chirping noise. I hear it at cruising speeds, and it's not a fast rapid chirp.It seems to be at a constant pace. I've readjusted the belt thinking that was it, but wasn't.With stock exhaust i know you can hear a lot of strange sounds that you wouldn't hear with loud exhaust. One other thing. is adding a K & N air filter the same as opening up or modifying the air intake when installing aftermarket exhaust?