trying to find smaller pulley for alternator
 

Have a 94 honda civic EX. I have a bigger alternator on it, but I am trying to find where to get a smaller pulley for the alternator. When the car is at an idle, the lights start to dim a little. Took alternator to shop to have tested and they said it works fine. It currently has a 2 1/2" pulley and looking for a 2". All pulleys I look at are underdrive for more horsepower, and I need overdrive. If anyone knows where to find it, please let me know. Thank you.