This high-quality all-steel part is a perfect replacement to the 2-piece plastic OEM unit that has a reputation for splitting and dropping your coolant all over the place. The stock unit has two thin halves of plastic glued together and an exposed lever arm. Some of the Supercharged 928's have accelerated so quickly - which of course include spinning up the water pump - that this valve has burst dropping all the coolant!
You do not have to be supercharged to enjoy the benefits of a closed all-steel heater valve - greater reliability and lower service/maintenance costs. This part is even $20 less than the OEM unit!