have you recently cleaned the KIPS valves?....
once they get cleaned of any carbon build-up, they get a little "loose", and yes...they can make quite a racket.
other than that, there's really not a lot you can do unless the valves, or the guides themselves are really worn...but it's pretty normal for them to be noisy.
If you use the sites search option, and type in "KIPS rattle", or anything like that, you'll find several threads on the subject.