Hi, I race for team Subway Yamaha Australia and we have tried both options (wr & yz). Both have there pro's & con's, but l think the yz is the better choice. ln saying that our race bikes have increased hp, but more importantly alot more torque than stock.This enables us to pull the taller gearing that the yz gearbox offers without bogging down (engine very sharp & pulls hard out of turns) but still have enought top end to handle the biggest straight. Another advantage is the fact that you require less gear shifting, this alone is a big plus. At most tracks that we race in the nationals l may only use 3rd & 4th gear,that helps me use less energy, but more importantly helps keep the bike balanced/stable when accelerating hard out of turns because the suspension is not interruped by gear shifts,thus keeping the suspension loaded & driving. We ran the wr in the 03' nationals with good results 2nd place for the season so the bike is more than capable. but if racing is your plan, the yz in my opinion is the way to go. If you would like anymore info let me know,cheers Adam.