Sorry I didn't need to add the bit about the spacers really lol
The lower the ET or offset means the further they stick out (giving better brake clearance) Althought you don't need ET15 or ET17 to clear AP 6 pots only ET33.
So you'll beable to machine the current ET15 down to ET33 if you like to get them to fit under the arches but still clear your brakes.
Iain is it a 3 Door you have?
Rich