I'm not sure if Unorthodox still offers a pulley for our engine, but it would be another nice item to have, maybe with a slight underdrive?

Does Audi have an OE alum alt pulley, or they are all steel?

pulley made of the same material. I would opt for having a core alternator rebuilt to output a few less volts/amps if that's the desired goal and keep the pulley small & light as possible.

Which would "lighten" the crank shaft pulley's rotational mass...etc

Yea, I used to be a 5.0 Mustang guy...<ul><li><a href="http://en.wikipedia.org/wiki/Underdrive_pulleys">http://en.wikipedia.org/wiki/Underdrive_pulleys</a</li></ul>

But a larger pulley on the alternator changes the gear ratio that much more. Making it easier to turn therefore "less parasitic drag" Kinda like the "granny gear" on your 10 speed.

Also to truly take advantage of the underdrive setup you would bypass the A/C compressor.

a preferred "over 15%/less than-20%" under-drive "ideal" ratio when going "either" way. Reason being the 300% difference between the stock crank and alternator pulley diameters.