Just wanted to know is there a difference in the aftermarket headpipes compared to the stock head pipes. My friend is looking to install the slip on ids-2 on his 440ex. Is there really a huge difference in the head pipe design or are the aftermarket manufactures just trying to sell u something you don't need.

 

If there the same size there shouldnt be no difference. But if it is bigger in will make it quitier and get the gases out of the combustion camber faster