I've searched but couldn't find exactly what I was looking for. Can anyone let me know if a slip on for an '06 YZ450F is a direct bolt on/fit to an '09 YZ450F ? The info I found through the search let me know that the '06 250F silencer won't fit onto the '09 450F, but that's not what I need to know. I'm guessing that the '03-'06's are interchangeable, and the '07-'09's are but you can't put a slip-on for an '06 onto an '09 (different pipe diameters) ? Is that correct ? Thanks for your help !