I can only give you info from my experience...I went to a wheel specialist who said they could help and they ordered 18" wheels to test and see if they would work, unfortunately the Brembo calipers are just too big and they wouldn't fit. The guys working at the shop were all shocked at how big the calipers were.
I ended up buyng another set of performance pack wheels exactly the same as the originals. Even these have minimal clearance fron the inside of the wheel to the caliper, but they are designed specifically for the Brembo's.
I'm sure you could find some 18" wheels to fit, but everyone I have spoke to seems to know nothing about the performance pack, which is pretty frustrating. So I gave up and went for the originals.
Good luck!
Not happy! another set of performance pack wheels = a fortune!! They are supposed to start building my 290 next week so it's probably too late to make any kind of changes I wish I ordered it without the king size brakes! Btw, are they any good? have you tried the standard ones? Would you have made a different choice from what you know now?