Thanks for the input guys. I find it interesting that most water pump I saw say that they have the "improved" metal impeller. Also, the water pump works fine on the car right now, but i don't know when it was change last which is why I am planning to do thermostat and water pump. JCL, you are right, the MTC part is cheaper almost the same price as the URO part. Now the only water pump I found that is Genuine bmw with composite impeller is refurbished. Would you put a refurbish pump or leave the one as is since it's not broken?

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2001 BMW X5 3.0 Sold
2008 VW jetta S
2006 Lexus Rx400h