Yesterday I got to ride with my buddy and his brand new left-over 2010 yfz450r Bill Ballance Edition. Only after market engine mod I have is the EHS air box. His quad is stock. We dragged down the road a few times he beat me 1st-4th but when we hit 5th I caught him. They have over 100lbs on us with the aluminum frame and what not. On the trails he couldn't keep up at all and it was even worse for him when we had to back up. I really appreciated the reverse watching him push his out lol. I was tempted to help but thats why I bought one with a reverse so I wouldn't have to do that. I was surprised that his quad did that well dragging though. I beat 700r's dragging but his 450r was faster if you ask me.
The yfz is meant to get up to speed quick because it's a track bike that's why up until 4th it's beating you. They aren't very good for long stretches of high speed. My buddy had one and would try to keep up in high 4th and 5th gears with my xx and raptors and his exhaust got destroyed from heat and his motor is a mess. His exhaust literally fell apart off his bike on runs even in the winter lol. Also he was all stock so no mods were causing damage.