is an underdrive pulley for a ej22 supposed to be alot smaller than the stock one? and will i have to get custom belts or something?

 

dont do it!!!! just get a Perrin lightweight one. Underdriven can cause problems w/ Alternator, etc.

 

Weight is the big improvement. Perrin, Cobb and a few other companies sell lightweight pulleys that aren't underdriven. I switched from a UOR underdriven to a Cobb and like the results. My lights don't dim at stopsigns/lights anymore.