Just dropped the C3 pulley off at the airport, HC...all snug in foam and spooning with a brand new idler pulley.

Krazy Steve is right: Don't overtorque the bolt! You'll want to because it simply won't seem tight enough, but just use blue loktite on it for peace of mind. You'll need to get a strap wrench. And I recommend putting on a new belt at the same time.

I'll say this about the C3 pulley -- regardless of what the dynos on different pulleys say, the C3 is a monster light-to-light. Wait til you add a tune!