I think if they are painted properly in gloss black then you would be safe, looking at the 2 pictures I feel the chrome grills actually date the front end of car. If the grills were to be painted in matte black for instance then yes they would look horrendous. After all BMW did bring out the "BMW Performance" range of black grills for some models like E92 and they looked very well imo. I think with the car being black and grills being black it will turn out very well. If it was another color say blue, red etc it may not look so good.