I put some visor trim rings on my headlight and passing lights today. Followed the directions and NO gap. And, didn't have to use any clamps as others have suggested.
no gaps for me either... though i did use a clamp or 2 on the headlight just to be sure. I think following the supplied instructions very carefully was the key however
Directions say to slightly loosen the original ring to allow the new one to settle into the space between the housing and the ring. You won't have a gap if you do it right.