My time to chime in.
I also picked up a FRP (non CF) rear diffuser from EVOR and had install issues because the plastic was warped. Needed applied pressure to secure and not even glue/silicon would hold it.
So... I had to do the next worst thing, add 2 additional screws just on the side of each exhaust tip (black screws) connecting the diffuser to the bumper.
Not noticable because it is black on black but would rather not have drilled 2 holes in my bumper because now i definitely can't take it off. If I did, I will have a bumper with 2 holes and glue jizz all over the back.
