I have a 2007 Mandalay 40E 400 cummins. I pull a Jeep. it never ran over 200 degree. My unit was made in late 2006 did they change the raditor size in 2007 models? also I can't get over 5.7 MPG I talk to a person that had a 2008 425 cummins and claims he get 9-10 MPG