Are you talking about the panel gap over the rear wheels? In my experience it's better to move the bumper up. Your success may be limited however. When my Roadster was new I complained about the uneven panel gap above the right rear wheel, trunk lid to bumper. Tesla made several attempts to fix it but every time they adjusted the bumper, something else didn't fit. At one point they got it right but couldn't adjust the latches so the trunk would open in the "fixed" position. I finally gave up trying to close the gap and decided I had to accept some quirks with a hand-built carbon fiber body. Not the answer you wanted. If you find any better ideas, I'd like to know, too.