I've done some research on this in the past, everyone I spoke to said changing an engine's crank pulley is a no no, because the pulley is balanced to the crank, changing it, changes the balance of your entire engine and reduces its life in a hurry. Changing the Alternator and Water Pump pulleys do bring benefits, wont be much of a difference in power but it's more in the responsiveness of the engine, it will rev out easier if that makes sense. Check out www.9thgencorolla.com a few of the members have the pulleys and let you know the results.