With this pulley you will see two primary benefits: Weight Loss and Reduction of Parasitic Power Loss. The super-light weight provides a power boost, while the underdriven diameter reduces power loss. The results is a more free-flowing throttle response and more efficient power production. This is an upgrade that most drivers can actually 'feel'.
Some believe that a lightweight crank pulley has an adverse effect on the balance of the engine. This is not the case with the Subaru boxer. The Subaru engine is already well balanced and the crankshaft is relatively short, therefore the crank pulley's balancing effect is minimal. Some also believe that underdriven pulleys cause accessories and voltages to suffer. This is not true. Belt-driven accessories are regulated, becoming less efficient as rpm's increase. This results in parasitic power loss. The underdriven pulleys reduce that loss as rpm's increase.
