I have a used FMF factory 4.1 for an 06-09 YZ250F, 07-09 WR250F, 06-09 YZ450F, or 07-09 WR450F. It comes with the aluminum spacer in the midpipe to mount on a 250F, to put it on an 07-09 YZ450F you have to pull the spacer out. There are some scratches and small dents that you can hardly see in the pictures, and really can't see once it is on the bike. I just repacked this silencer, so it is ready to bolt on and run. Looking for $250 or best offer. My email is kdhumphr@syr.edu