Originally Posted by fbm3cab
The 3M has held up fine and its been over 2 years. I don't feel it will perform as well with larger spoilers and diffuser.
My BMW performance spoiler, Arkym diffuser, and Arkym lip stay on just fine at 150 MPH. I would NOT permanently glue anything to your M3, especially since it has special paint.
You also have to consider that if the fitment of your parts is off just a bit (which it most likely will be), you will have gaps regardless and the adhesive won't bond properly where as foam tape has some thickness to it.
My parts have no gaps caused by tape. The only gaps are due to slight fitment issues (tolerable ones IMO). My BMW performance spoiler fits perfect with no gaps at all, tape or otherwise. My Arkym parts have some extremely minor fitment issues but enough that I am not confident that liquid adhesive would bond properly.