Basically it just adds a larger port for oil to pass through to lube the bottom of the piston the way I understand it. Do you have to do it? No. It is best to do it as bigned said. I couldn't tell you if mine was done or not. Not by me it wasn't.

I'm not sure what it would cost or if you can have anyone even do it. It is a modification so I don't think a Yamaha shop would be up to it.

 

i bet if u went to a yfz450 forum like yfzcentral.com u would get more info on how to do it and how much it cost. from what i hear its pretty easy

 

<div class="FTQUOTE"><begin quote>Originally posted by: bigned1904

... what i hear its pretty easy</end quote></div>

Oooo. It's not installing new exhaust and re-jetting easy. I believe it requires a pretty big tear down.