+1 on OEM cooling components. As one example, the hoses are shaped in a specific way and have quick-fitting plastic connectors on each end, with rubber O-rings integrated on the inside. The plastic connectors are oriented in a specific way to line up with the keyed inlets and outlets of the thermostat, radiator, etc. Removal and install is literally "a snap"!
As specific as the hose design is, I wouldn't want to compromise proper fitment by using another brand of hose. That is just my preference. I'm sure others have had success with aftermarket hoses.
The Stewart-vs-OEM water pump debate will go on forever. Some people here perceive it to be more durable simply because the impeller is metal and the pump looks/feels prettier. Unfortunately there is no real statistical data on this forum to justify the $100 price difference. It's really a matter of personal preference. Stick with OEM and change it at regular intervals.
BMW CCA member - Peachtree Chapter
Last edited by LeMansteve; 08-30-2012 at 11:17 AM.