Which of these atvs is better for an enduro race? The Yamaha Grizzly 660 2005 or Kawasaki Brute Force 2005?

How can I make them fit for a race?

Which will have more seriously complications after or during a race? (I heard that the Brute Force brakes down more than the Grizzly)

 

brute force, or prairie 700

 

Something that will hold up. The Rincon won that Baja 1000 a few years ago, and its by no means the fastest thing out.