I know exactly what you are describing - Did both of my thrust arm bushings this last weekend. The plastic box is in the way on the driver's side. It is an airbox with some temp sensor (I think) at the front behind the grille, and looks like it vents upward along the side of the engine.

To get the driver side bolt out I took the two screws out to be able to move the wheel-well plastic lining. After you get access to it you can see to bolts above the airbox. Remove these and you may have enough room to get the bolt out.

I had to unsnap the sides of the airbox and collapse it into itself to get enough room. Luckily passenger side doesn't have this.