2009 yz450f I found out the hard way that a full Dr. D Exhaust causes interference with more than just the oil filter cover bolt. I bought a skid plate from emperor racing and tried to install it. The top of the wing on the right side hits the header, not allowing the mounting bolts to line up. I will be able to trim the plate to make it work. Just thought I would give the heads up that Dr. D full exhaust + emperor racing skid plate = interference.