I have been running the 285 kit on my 05 250 for almost two years this last fall I put a wide ratio tranny in my Yamaha. I have a friend that just got a 09 450f. No matter where we race he can only beat me on top end IE over 75 MPH we are running the same gearing IE stock for the kx 13-50 I'm running the same on my 285. He just shakes his head,and says that thing is really fast. So last week he ordered a new bomb header and new computer programmer. He says it is only to make it start better. But i know the truth he can't stand that my lowly 285 yz is a fast as his brand new fuel injected 450f. I highly recommend the staff at Max RPM they have been awesome to deal with.
raymo