I don't know much about it myself but I think scarykxer has one with the CR500 conrod in it?
I think they are also half a mm shorter than the KX conrod and might even have a different bore at the small end bearing.
I remember looking at the specs ages ago when Zanx had the bike that scarykxer now owns but I can't remember the exact sizes of the rods.
With it having a shorter rod it will affect port timing slightly and unless you do something with the head your compression will change.
Aparently it's something the motocross sidecar nutters do
<Post edited cos I have had a look on a different thread and CR rods are shorter, not longer and I am more confused now than before>