took a chance and a straight used header off of ebay for cheap since mine has a dent in it. and thanks to the guy who bid me up five bucks if you are on here. seller claimed he did not know exactly what it fit, but had bought it for his wr450 or his brothers yz450. i wanted to run it by you guys and see what you thought. have not measured anything yet, but holding it next to my old one that is still on the bike it looks similiar. the part number stamped on my old one is y-5tj, and on this new one is y-5jg. does anyone know what it is off of, and will it fit my 2005 wr450? looks to be titanium, not stainless. but who knows.