Hi,
Thought we all say they have the "same drive-train" doesn't exactly mean they are 100% the same.
Without diging into every single gear. I know that the rear differentials is the most import factor when it comes to this.
The Foreman rear has 20p - 41r teeth per rotation.
The P5 rear has 21p - 51r teeth per rotation.
Someone else will have to figure up the math on that.
But it more less equals out to this:
The Foreman will be faster with less low end power vs the P5.
The P5 will be slower yet more powerful then the foreman because of the lower gear ratio.
If you were to swap the rear ends they most likely would be about the same.
Hope that answers your question.