I actually bought an 07 YZ450f and a 07 KX450f. I don't know why I got 2 different brands this year. The YZ handles a 100 times better out of the box. I don't know about the motor I never rode it stock. The Kawi has an awsome stock motor but the suspension sucks. Bad!!! It's tall, wants to push to the outside and stands up in every turn. Out of the box I think the YZ is a better deal. You get good bars, rims and a true 5 speed. Set the sag and it's ready to ride. In the end I decided to race the kawi but now after everything it feels just a little better than my YZ. I don't know what level you ride at but you will spend less money on the YZ.