I'd like to know the reasoning behind this too... What happened to your previous fc waterpump pulley you need to replace? If you're still using the stock and want to get a UDP setup, why not just get the ATX crank or the 2pc FC setup. If you already have a crank udp and want a better water pump pulley, you won't see much of a gain at all. So many scenarios =0.
Well I ordered the AFX UDP because I heard it underdrove the accessory's a little more and was the lightest. Then I figured I'd just get the FC waterpump pulley to help me out a little bit more. If it won't really make much of a difference then I won't buy one. I was just wondering b/c I saw some guys had an esslinger pulley with a FC waterpump pulley.
you cant really just slap on the FC water pump pully if you have a single crank pully, the water pump pully on the FC kit is larger to make up for the size in the smaller diameter of the FC crank, therfor allowing you to use the stock belt
You're already underdriving your accessories to the max with your atx, you *may* not want to further reduce your water pump, especially in CA?... You'd also have to get a new belt, too. The only reason as said, the fc 2pc goes on the stock belt, is the crank and water pump diameters are swapped.