Underdrive pulleys have long been around and are a great way to release more power. The kits does this in a couple of ways, first the reduction of reciprocating mass the second to underdrive the accessories. Once installed you will notice a improvement in throttle response. This kit comes with the new harmonic balancer & a new water pump pulley. A FG 5.4 lt engine will require a new BA or BF belt at additional cost. 00031987