[Perfectlap]

stop by the dealership and ask for the boxster side skirting clips. They are not expensive. And like he said ^ the double sided tape is used after prepping with alcohol.

however...Fiberglass is what I have and its hit or miss. Hopefully the fit is right. Unlike polyurethane which is made from a lazer cut mold that is exactly the right size, fiberglass is made by hand and precise fit depends on who is making it that day. Make sure you get the body shop to do a test fit before you committ to having them paint it. You don't want them to tell you after the fact that it required 5 hours of shaping to fit you car and there goes the $500 you saved.
You want no surprises. Agree to a price before they get started and tell them that you expect 100% guranteed satisfaction.
Bodyshops see Porsche and think they can charge 8X's the usual fee.

p.s.
Make sure they are using OEM paint and not what was left over from the last car they painted of the same color. low cost Bodyshops try to do this with standard colors like Black and white.