Mine took a ton of work...by someone else. I wanted it done right and I'm not talented in body/paint.
First, they're too wide for standard fenders since they are designed to mesh into flares. So they have to be cut and reprofiled.
Second, there is no top lip to accomodate vertical fasteners, so you have to attach through the face leaving messy fastner heads exposed. I had a lip put onto the top of mine for a clean finish. The top was wavy and not cut straight anyway.
Third, one of the air vents was crooked and had to be cut out and re-glassed.
Shoddy workmanship and horrible fit.
I got the rear valence from morespeed performance. Much, much, much better and nice design.