Well after owning a KTM 300 and a WR 450 I decided to tackle converting my 09 YZ 450 to a wr side access air filter. Bought a very slightly used wr subframe, airbox. Used a new wr seat,new wr side panels. I modified the yz rear fender to work. The only subframe modification I had to do was to cut and re-weld the left lower subframe tubing to match up to the yz frame. Kind of expensive but I really like the ease of the side access.