AVCS in the STI explained

[Sabre]

"The MY02 STi also brings Subaru's new AVCS (Active Valve Control System), which varies inlet camshaft timing over a 35-degree range to improve emissions, tractability and low rpm torque."

"AVCS is NOT anything like VTEC. VTEC is the changing of the cam lift/duration profile. AVCS does NOT do this. AVCS merely changes cam phasing or timing, like adjusting the cam position on the timing belt all the time, this is exactly how vanos and VTC work."

How it works:
Simple
Simple 2
Great PDF on it
About half way down


Lot's o good read'in. Sucks it's only on the intake side. I would really like to see it on the exhaust side too. There are rumors about it on 06, but nothing conrete.

I'm going to throw this up in the FAQ section too...