[davidlee]

I think 1/4" is too close. Torque and heat may cause trouble. You can use a dremmel tool with a drum sander bit or a router type bit to enlarge the cut out.I know you said you car was all ready painted but that should not be a problem. Get a small amount of touch up paint and brush in the inside lip of the opening. I know it sounds crude but I had to do it my car. Once you get the side pipes installed you can't see the touch up work. If you angle the grinder slightly inward you won't effect the paint on the side of the car just the paint on the edge of the opening. I hope this helps. And oh yes I did cringe when I first put the grinder on the car.
David