Bolt on and go, just remove the stock carriers and rotors and replace with these:
2X BMW P/N 34116769097 caliper carriers stress-relieved and re-plated to like-new condition before installation.
2X BMW P/N 34116794427 "Brake rotor, light blue, ventilated" 330mmX24mm Z4 rotors
Rotors and carriers have <7000 miles (see pics).
$250
I also have a PAIR OF Stock calipers with approximately 27k miles available which include Bimmerworld solid guide pins and Stoptech pads. Make me an offer.
Prefer local sale.
Shipping at buyers expense.