|1.8T Underdrive pulleys (2-6 HP) - $200-400|
Underdrive pulleys are the round metal parts that your belts spin on. The theory behind aftermarket pulleys is lightweight. The spinning pulley is lighter and therefore spins easy and does not consume as much power from the motor. These pulleys typically come in various colors and you can replace all the pulleys including the crankshaft, water pump, power steering, and alternator pulleys. Gains from these pulleys are minimal, roughly 2-4HP for a VW 1.8T with just the crankshaft pulley and about 4-6HP with all pulleys replaced.