I made a thread about fitting VW mk2 fender flares to GD sedan fender before :
I am still at the process of building the gd sedan, so I haven't gotten to the body work yet. But I bought an 02 impreza wagon as a winter beater.
Since I had extra set of these flares I wanted to try them on the wagon.
The fitment couldn't be better. They stay on the arches flush with only 3 screws.
If you are going with wide wheels you will have to cut your wheel arches (~ 1.5") and maybe pull the remaining (fender roller) to make room behind the flares for the tires.
These fender flares needed very little trimming. I will take pics of what needs to be trimmed when I do the other side.
I didn't get mines from this website but this could be a source to buy them :
Some pics :