Hi,
The only picture ive seen of your car is the one in this post,looking closer at the picture it looks as though the wheels are level with the wheel arch,was there no option of a better wheel offset so the wheels could sit more inside of the wheel arch?.
The other option might be to have the inside of the wheel arches rolled giving a little more clear clearance then it might be possible to lower the car.
Your car does look nice with the 20s ;)
Chips..