so far as I understand, F50 fronts, F360 rears to maintain balance. Rotor size is more for heat dissipation and of course, dictated by wheel size. As I've decided that 17" is the optimum wheel diameter for my R32, 355mm rotors are out. I think 343mm is about as big as I can go.
Haven't yet decided to to my calipers - did everything else and have great brakes as a result, but I don't think they'd last more than a lap or two around the 'Ring with the stock rotor size. But for the street, where minutes pass between hard braking stops, I have never, ever felt that I needed more brake - tires start to lose traction and sometimes ABS kicks in on dry pavement.
But a nice sexy set of brakes would be nice someday. But more bling than necessity for my needs, and I'd need seven grand to burn to make that move - I won't "upgrade" step by step as many do, as big fronts and stock rears throw off the braking balance, and unless I had a brake master cylinder that was precisely rebalanced (or threw out the ABS and went with twin masters), it won't help braking performance overall, not nearly as much as pads, rotors, fluid, braided lines, etc. Remember that brakes have to work while CORNERING and while huge fronts and stock rears *might* improve straight line performance (and there have been tests in US import tuning mags that suggested that big front-only upgrades didn't), try trail braking with such a brake setup. Be sure to wear your diapers as you shit your pants when the car gets all out of sorts.
When I upgrade my calipers, I want black. Red has become too cliche. Maybe I'm thinking that because Brembos are now optional on the Hyundai Genesis coupe, and now tons of Hyundais are running around with bright red genuine Brembos.
With big money, the coolest Brembos are the monoblock racing calipers, with the logo that looks hand painted and the grey metal finish. Cost a fortune on cars, but for some reason they're all over the bike scene - stock equipment on Ducati and BMW HP2s.