Mine is (single GT on a V6) just an eighth of an inch clear most of the way around the cutout. Thing of it is, when you are going slow, not much heat energy is radiatingfrom the surface of the tip. When you are going fast (high engine revs) and pumping out the heat, the car is moving fast enough to dissipate the heat in the airflow.

Before I put on the GT muffler, I painted the visible parts black, including the tip, with caliper paint. I drove around town for several days and it never got hot enough to "cure". Then I drove a half-mile in second gear, near 50 mph, and could smell the paint (and maybe the wax on the bumper cover) get hot. After that, the paint was cured, and the tip never got hot enough again to influence the wax on the bumper. It would, however, burn the fingerprints off your fingers, if you touched it at the wrong time ...