the moco dont want no-one tampering with epa legal emissions equipment therefore in order to encourage the use of said aftermarket performance equipment without incurring the wrath of the epa god's they put a little disclaimer on such off road use only parts. seems the moco has no legal authority to tell the end user what they can or can't do with their personal property. it's a rather clever way of telling you that they cant condone the use of this type of product on their motorcycle while simultaneously letting you know that it will run better if you install it.