no problems with scrubbing or anything on lock, i have about 3 screws holding then in, and 2 little clamps on the metal wing holding them in, i did not want to drill into the metal to fit self tappers, so used the universal clamps instead
I am lowered 30mm also.
Infact.. i did once get them scrubbed, I was going over a little ramp that was like this ^ and when the front wheels touched the ground, the mud flaps touched the ramp, however any mud flaps would have done that with the shape of the ramp i went over
My dealer said S3 mudflaps are not available, so we tried a set of front A3 ones, they didnt fit, there was a semi circle bit cut of them for the std a3 sideskirt shape to fit into.
So i tried the rear one and it worked fine