Call Dan at Power House
He knows YFZ450's like the back of his hand, and a GREAT guy! Well he know all quads, and has a dyno in his shop so he can get you all dialed in after what ever you have done to your bike.
Power House Racing
3834 Schiff Dr.
Las Vegas, NV 89103
Located in The Center at Spring Mt. in China Town
contact him at 702-227-1238.