MINI Cooper Harmonic Damper
This is a great upgrade to the stock Cooper S Harmonic Damper which can fail over time. Both stock and 2% larger diameter than stock pulley versions available.

Best reason for a Harmonic Damper that Balances Vibrations
Consider that there are four controlled explosions with every turn of the crankshaft in a V-8 engine. At 7,000 rpm, the spark plugs fire off an air/fuel charge 28,000 times every minute.

From the driver’s seat, it may feel like the engine is providing a constant source of power, but the events taking place inside reveal the contrary. When the cylinder fires, an expansion of gasses from the burning fuel places incredible amounts of downward pressure on the piston. Of course, that’s what we want since the engine is supposed to burn fuel to produce horsepower. Unfortunately, that force is neither smooth nor consistent. The force of the burning fuel pushing the piston down the cylinder bore must be converted to a spinning force by the connecting rod and the arm on the crankshaft. Plus, when the piston is being pushed up the cylinder on the compression stroke, the force is acting in the opposite direction.  The rest of the story can be found here!

For a "Value Line" Lightweight Crankshaft Pulley, see NME5038