Drilling Chrome Bumper

Use a bimetal hole saw as stated earlier. I would first drill with a small 1/8 drill then open up to the pilot drill in the hole saw, this will prevent drill from wandering off location, if you have a center punch use it first. Run saw slow so it does not burn the teeth and dull them. Use a soapy water solution in a spray bottle to keep hole saw cool and lubricated this way you are not breathing in smoking WD40, have someone spray coolant for you as you use both hands on that drill. Use a drill with low rpms and high torgue and watch as you cut through because drill can grab. Finally use a half round file to deburr your hole then seal edges.