Regarding brakes - get a BBK. I installed the StopTech 380 on the front only and couldn't be happier! Don't waste time and money.
I went through the rather expensive route of brake fluid (Motul 600 and 660), PFS 06 pads, Pagid Yellow RS27 pads, Carbotech XP21 pads, Cantrell brake ducts.
The result was pads lasting two days instead of one day, and replacing the stock burnt out calipers with new ones. Its a bummer ending your track weekend early because you've burned through $400 worth of front brake pads.
The BBK on the front has meant the pads last 5 days or 6 days, and the braking is much much better. The pads are cheaper too.
E92 M3, Competition Package, MDCT, Ground Control Adjustable Camber plates, StopTech 380 BBK, OEM exhaust mod