Change that to 2003-2009 yz450f and all the wr450f's . The 250s have different diameter headers going into the header but the mufflers will match up depending on header diameter. (sorry about the confusion) But yea. I cant guarantee fitment of EVERY exhaust system but mounting points and where the header meets the muffler should be the same. On my 07 i have a 2003-2005 yz450f procircuit header with a gytr slip on. Ahh ok, Thanks man! Here are a couple pics of it finished boys.