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Quote Originally Posted by mcamera View Post
Does anybody else feel like this is optimistic? The crank pulley is the same diameter as the OEM pulley so it still has to produce the same amount of torque to turn the alternator on our cars (and maybe the AC for some people). You can make the pulley lighter but to say it reduces so much rotating mass (-4lbs) that it's equivalent to 100lbs off of the curb weight sounds like a stretch.

Attachment 190276
I have that pulley in red in my 818. It looks way faster.
Hahaha that sounds more accurate than the advertisement

I believe lightweight flywheels reduce enough rotating mass to make a noticeable difference. Those usually save ~12lbs and still have to turn everything between the engine and wheels. Same concept here with the crank pulley.

From reading many threads, there are claims that Subaru doesn't use their crank pulley as a harmonic damper. Including some emails from Subaru customer service saying it's just a pulley, not a damper. That being said, I agree any benefit is probably small enough to not be worth the risk or $150.