However, for the sake of making sure things are done right, I don't recommend installing the fog light ducts with the fascia on. Fog lights can be removed with fascia on, just not the white fog light housings that the lights mount into. What method are you using to secure the ducts?
1993 Nissan 300ZX Slicktop (Oxford Gray Metallic) 1992 Nissan Skyline GT-R (Gunmetal Gray) - Long Live the Z and Godzirra! - "Love cars. Love people. Love life." - Mr. K.