I've been spending some time getting the caliper brackets just right using a 15" OZ Superleggera. It was tight to say the least and with 20mm spacers and the caliper spaced perfectly for 300mm Grand Scenic discs, the caliper fouled on the inside of the wheel. I had to space the wheel another 8mm out to get it to clear.
Possible solution were:
1) Custom 2 piece discs and bells from Hi-Spec with a larger offset taking the caliper further away from the wheel but worked out it would foul on the hub at 7mm.
2) 30mm spacers.
Both options had problems so thought I'd try the my other set of wheels which are 2118's and guess what, there's loads of space without having to do either option. Couldn't believe it when there was about 8mm clearance on the 20mm spacers. Would probably work with no spacers as well.
So looks like I'll need to sell the superleggera's and buy another set of 2118's with ET38.
Phone pics are poor but you get the idea,
This means the grand scenic discs are back on saving a fortune on the custom 2 piece discs. Maybe not as bling but definitely cheaper.