Two plates required in Massachusetts.
I need to add a front plate bracket to get my '06 on the road. What are the options? Can it bolt on, inside/under the grille? I don't want to drill holes in the bumper skin. Are there OEM and aftermarket brackets? Can it be wired direct to the lower grill mesh with spacers to allow air to pass over and under the plate.

 

If the DOT up there allows this, why not put the plate in the windshield using silicone suction cups?
It's legal in Texas to display the front plate there, so I do! It's mounted to the right of center, out of my way behind the RS wiper blade. (You can't see it in my sig cause I usually take it out for photos and meets.) I don't even know its there most of the time.

If you can't do that, there are plate brackets that screw into the tow hook location on your front bumper?

Or you could attach it to the lower grill as you already suggested.

The sky is the limit, as long as the Massatwosh*ts DOT approves.

 

+1 on the suction cups. It's what I use myself. As for the tow hook route, that's a no go on the normal 6, we have no easy access port on the bumper, only the speed 6 has that.

 

Oh, I didn't realize that. I thought the 6 series had them too. That's a gyp!!
If you look at my sig pic, B-R, you can just see where the tow hook would go on the RS front bumper... left from the viewpoint of the picture. It's that little circular thing attached to the bumper cover above the fog light just right of it and below the RS headlight.

But yeah, if its legal where you are, I would go the windshield route. I wouldn't ask for trouble if its not though.