I have the GYT-R CDI on my YFZ along with a HMF Balance-Series Full Exhaust, No Lid, Jetted. I noticed slightly better throttle response and alittle better pull on the bottom end due to the new ignition timing of the CDI, also the overrev is a great thing to have. It shouldnt cause any harm because the CDI basically just takes the Rev limiter up to the same as the YZF dirtbike, so it should be fine.