Solved!!!! Fumes in interior

I have a friend , that once had a 69 mach 1 with a 390 4 speed, he tried for a few years , also same thing , changed trunk seal , pcv vented different ways , he either had to have all windows up or all down , he moved his exhaust tips, out farther away from the bumper , and this worked .They figure it was creating a vacuum and hauling exhaust up and in the side windows.But i find every time i take my dart out i smell of exhaust when i get home .