My only experience with the Boyesen Rad Valve was with my kdx. After carefull jetting, etc., I came to the conclusion that the Rad valve provided very little difference over using the stock reed cage with the Boyesen replacement, power reeds. Two of my riding buddies (same model bikes) ended up just doing just the reeds and I was unable to notice any appreciable difference in the way theirs ran compared to mine. BUT, I did recently put the new Delta Valve II (Moto-tassinari) cage in my 98 yz and was thoroughly impressed with the difference that it made. I strongly reccommend the Delta Valve.