Which water pump housing should I use?
 

Is it better for me to use a S4 N/A water pump housing rather than the TII water pump housing on my TII engine? I can't remember but someone told me to use the N/A over the TII. Is there a big difference?

The N/A will not not have the coolant return line for you turbo. If you have an aftermarket turbo setup that is oil cooled only then install the N/A housing, to eliminated a potential coolant leak spot.

Like was posted above the only difference is the coolant return nipple on the suction side of the TII water pump housing. Other than that they are identical. If you're using an aftermarket turbo that is not water cooled then you can use an NA pump housing instead of capping the nipple on the TII housing. If you're using a stock turbo or a water cooled aftermarket turbo then you'll need the return nipple on the housing.