If you have the money, JCW
Brembo BBK is very nice upgrade, both in braking power and, maybe even more importantly, in the looks :-)
They appear on eBay from time to time. I bought them as new for £900 incl. Goodridge stainless hoses. Pretty sweet deal if you ask me, I can't wait for better weather to install them :-)
Front kit is available there right now from mjrminimattltd and I'm sure minimatt will have the rear kit too if you ask him (I bought full kit from him).