Looking from pictures mind you, I get the feeling that the KX250 pipe would work with the KDX bike. The dang pipes are way similar. Given the huge variaion in physical appearance between the stock, 2 FMF pipes and the PC pipe, I can not imagine the KX250 pipe would be any better or worse. This is more so in the case of my hybrid where I need add a longer head tube anyhow. Here is the question, does anybody have a KX250 pipe layinng around for me to test this thoery out with? I may need to fab on it so I would need to keep it. If you are in a position to help let's try it out!