Good to know!
My 18x9's have a 35mm offset, but I run 13" Dr Diff rotors and 3mm spacers, so my effective offset compared to stock 73+ rotors is 27mm now. I haven't done anything to the fenders and haven't had any problems, but I still just lightly rub the frame in the back at full lock. Just enough to rub the paint off now. I also had to cut down the corner of my Z-bar brace. Based on what I've seen for steering stops on some other ball joints I think my lower ball joints allow a little more steering than others.