I just went to my local dealer and checked out the 07 WR450. I did see one down in Baja during the Baja 1000 race a couple of weeks ago. The guy riding it flew his in from Japan, (Cheater). He had a IMS 3 gallon tank on it. He said all he had to do was remove the smog stuff, and buy the YZ Radiator Shrouds to make it fit. He was using the IMS Tank for the 2006 YZ450. I have a garage full of parts ready to put on ,and I will take notes on how to remove the Smog crud.