Unlike you guys I have a yfz450. I know it is a little bit slower than the bikes, and i want to change that! I would have bought the bike, but when all your friends ride 4 wheelers its hard to buy a dirtbike.(cant learn from each other mistakes) anyhow i heard to gain a little more ponies i can install the wr crank in the yfz with no trouble for 380.00 (includes everything ,piston,rings,crank,blah) then i will be a true 450, but why spend the money to update to a true 450?? I was wondering what kind of options you wr owners have updating the performance of the bike, and whats proven to be the most gain.. (what i want to do is install a wr crank kit in my yfz and maybe bore it out a couple of mm's.. i know you all have a yfzthread,but not many users, and you wr guys been awhile for a little longer..