Klaptrap24;121441 wroteso what exactly would be the benefits and drawbacks of a lighter weight+smaller pulley? I was thinking of getting one for my NA b230f
I'm not an expert on the importance of the damper in the B230 pulley, but looking around online it seems there's a large number of people using lightened pulleys with no damper, and having no noticeable running or longevity issues. The damper is designed to absorb harmonic resonance at particular RPMs, and it's commonly asserted that unless you're using a boat or some application where you set the RPM and leave it there for long periods of time, the damper is probably not that important.
In terms of mass, you want all the rotating components to have as little inertia as possible (with exception of the flywheel where you want some mass to make the engine transmit power smoothly to the transmission).
The moment of inertia of any component in the rotating assembly is a function of its mass and the distance from the centreline of rotation, so mass further away from the centreline requires more torque than mass near the centreline. Thus, reducing moment of inertia reduces the energy needed to accelerate the crankshaft.
The other changes would be a reduction in work done turning the coolant pump and alternator, which would mean more power going to the transmission. You might need to tweak your alternator and thermostat to compensate for those changes.