The underdrive pulley is going to be replacing the harmonic balancer. And which bearing are you talking about?

 

i've heard that installing an aftermarket pulley would kill your crank bearings over time, but a lot of people seem to have been fine for a long time.

are there any ill effects, short or long term for the underdrive pulley (or any of the other accessory pullies)?

 

Check here:

http://www.supras.com/~riemer/sonictech/dinantech/dinan.html

This is for a BMW, but it applies directly to any engine with a harmonic dampener. I would not install one on my car, suggest someone else install it on their car, or even acknowledge the companies out there that manufacture these pullies as anything but snake oil salesmen.

http://www.dsmtalk.com/forums/showthread.php?threadid=709

 

I believe that the pulley that Buscher sells contains a harmonic dampener like stock