Drill a pilot hole and then use the proper sized Greenlee Punch (which utilizes a 1/4" to 3/8" bolt and nut to "squeeze" the punch jaws to a nice clean perfectly round hole of the proper size. No streatched metal... just hole. I would suggest putting it over the dome light if I put it in the roof. I prefer my holes in the top rear fenders. Bill K5BDZ