http://www.nonstoptuning.com/NSTPULL...tToySciXD.html
that is the only pulley that i have known to be available to our cars. i personally have one, and it has been just fine.
http://www.nonstoptuning.com/infoPageUnderdrive.htm
this just gives a good description. it says it takes away power from other accessories but i havent noticed any change in mine personally, like AC.