The problem is the tabs on the bumper that the diffuser bolts to is bent down. Causing the gap. The tab is part of the bumper, so it is plastic. The fix would be taking a heat gun and heating up the tab, and push it back up. Then leave it cool in the new position.
I'm getting ready to replace my 2nd diffuser. I've chewed 2 of them up so far. And I have broken one of the tabs on the bumper.
