I have some 1:4 window louvers on my new edge v6 since about April now, and side scoops from the same company, mine warped a little in the paint process but went on well, just make sure the area is really clean.
I also taped off the area where small crack between the car and louver was and bought some black silicon(my car is black)
And pinned some PVC between a wall and the louver and put some silicon in the crack and smoothed it out and let it dry on. And u can't even tell, and it held on nicely and won't ever budge again.
For any other color I would use clear.
But that's how I did mine.