Did you ever get around to taking photos of the fitment?
I've been shopping around for rear diffusers, my rear bumper has a few scrapes/dents on the lower part of the bumper from parking in LA (and getting lightly rear-ended once). (Not me love-tapping cars, other ppl bumping me!)
By the looks of it, this diffuser would cover up most of the wounds. It looks similar to this one on ebay:
Can you ballpark how much it cost to paint it as well? Thanks!