Over the last few weeks, my plastic panel has continually come off. If you are lowered, and scrape, the clips seem to eventually come out.
The first time, I was on the highway, going around 80-85, and I heard a loud flapping noise, almost like a blown tire or something. I pulled over and found the plastic piece hanging on by one clip. The next day I went to the dealer and bought a handful to replace every once in a while as they fall out.
The problem has become more frequent and my plastic clip bills are going up
I am guessing the more I scrape, the more imperfections there are on the under body and somehow air is getting into the cavity and forcing the panel out.
The second time the issue happened on the highway, I was headed to LA, going around 85 and heard a LOUD popping noise from the front, like something had knocked up from the road. I pulled over, and the piece had dropped again. The noise was the clips ripping out.
On the Nismo model, I definitely notice a serious aerodynamic issue without the plastic flap. If I go over about 80 - 90, or if I am driving into a strong head wind, a loud vibration noise comes from the front bumper if the flap is not in place. When I get the car on a lift again, I will investigate more, but I thought I would add my story to help.