its not necessary...but its easier to.
the grille is held onto the bumper by 4 screws on the bottom (not to mention the clips on top)...you CAN reach in through there and feel for them to remove (what I tended to do when I changed mine (3times)...but if you take it off its easier.
If you want to leave the bumper on, remember there are 4 screws and they drill up from the bumper into the grille.
|