You won't get a straight answer on this, to many variables. Rider ability is the biggest one, traction is another, machine setup still another. You have to figure, a 700XX is over 100 lbs heavier then a 450 based machine, that is alot to make up. You could beat this to death all day on the internet, just race him and see how you do, then you will know.ok so what you mean is i have to have atlease 5 hp more to beat the 450s ???