I have a d16y8 that I rebuilt for boost and after I got it tuned it keeps overheating while driving on the freeway. Its fine around town but as soon as I get on the freeway and cruise at about 70 it gets hot. I took out the thermostat to see if that was the problem but it still gets hot. I have an aluminum 2 inch core radiator also. What else can I do to cool this thing down. I don't want to mess up my freshley built motor. Help me out h-t.