I see that Rick's used to make these... But they are hard to come by.

Does anybody else make lightweight pulleys?
Would they provide any gains on our cars?

I know that on M3s, UUC Lightweight Pulleys help a fair amount (relatively speaking). And similarly Unorthodox Lightweight Pulleys help for some other Acuras and Hondas.

Anybody know who makes some for the S2? Or if there is any potential?
I'm sure this has been covered a bajillion times before, but we all know how well the search works.

 

Don't confuse "lightweight" with "underdrive" pulleys. They are two different concepts. "Underdrive" pulleys changes the speed at which driven accessories run, thus saving some power. For example, a water pump would pump less, as would an A/C compressor. An alternator would also not spin as fast.
A "lightweight" pulley is the same diameter. It's just made of lighter or less material. I think Rick's sold the "lightweight" kind.