So I bought an Alpina air dam from Couple King. Got it back in January when the price was higher, but it is a nice piece. Pre primed and nearly ready for paint. I had to figure out how to attach it (black stainless screws) and drill holes in the air dam and paint to match. 12 screws, ~ 6" apart.
When I was first fitting it, I thought something was wrong. The gap between the nose and the center section seams too large and it was not going to fit right. Could be my car is bent... but I could not figure how. The screws pulled it in, but it is still higher in the middle than I had expected. After looking at lots of pictures of other cars with this air dam on them they too have this rise in the center.... mine might be a bit more.
Anyway, I painted it with spray can spray paint and clear coat to match the body color. Got the paint from an on line touch up paint supply, matched really well. With it being such a dark color it is hard to notice any problem with the mounting.
I added a strip of foam weather stripping between the air dam and the body (closed cell foam) to keep out water and dirt.
I like how it turned out. It's subtle, but still aggressive looking and I think it finished out the front of the car nicely.
There isn't much information about fitting this style air dam, and I have gotten so much information from this forum about other things I hope this helps someone with their project.