the car has been mini tubbed and the rear has been narrowed. I can't remember, but I think it was narrowed 2 inches per side. I have wheels with 4.5 inches of backspace. I had to trim the inner lips on the inside of the wheel wells in the quarter panel. not take them all the way down, just trim them. now on the inside I have about 2 inches to the sprin. I also had to have the bottom of the wheel wells cut and moved forward toward the rocker panels to keep the slicks from touching them. my body guy moved them 3/4 of an inch forward and the tire just barely touches the paint during the burnout. it doesn't even leave a mark on the slick or rubber on the body. just kisses it. however, if doing it again I would make sure it was moved about 1 1/4' at least.