I have a stock 2008 WR450F complete exhaust on my 2008 YZ450F. I'm having an issue with the muffler melting into the right side panel and the right edge of the rear fender underneath the side panel. It's at the very front on the muffler, right before the pipe drops in diameter and transfering into the midpipe. Does anyone know if this muffler isn't made to fit a YZ, or there are differences between the YZ and WR that woudl cause this issue? I didn't thinkt here would be any issues since aftermarket exhausts fit both models? I didn't have an issue with the stock YZ exhaust. I'll post a picture when I get a chance.