You'll need spacers with most wheels with the Audi TTRS brake conversion, most likely an 8-10mm spacer. I'm opting for the NQSBBK and I can run it behind my BBS CH without spacers, it uses the stock 312mm disc and is about half the price of the Audi TTRS set up but still uses a 4 piston Brembo caliper (from a Porsche). Cheaper in the long run to service too.