why is one better than the other?

The 3 liter that's stuffed into that engine bay leaves barely enough room for anything, let alone forced induction. That's why the the B5 S4 wasn't sequentially tuned with it's turbos. There's no bloody room! But if I had to do one or the other, my only choice with your motor would be to supercharge. There might be a way to fit a centrifugal blower in there somewhere, but the only question is where. As far as turbos go, there is just no way you'd be able to safely squeeze any kind of usefull turbo underneath the manifolds in your car. Think it over, and kiss your waranty good by.<ul><li><a href="http://www.cruisecam.com">http://www.cruisecam.com</a</li></ul>

PES is working on a 3.0L 30v setup just like their 2.8L setup...Wait for that to be done.

MTM has one on their 3.0 Cab. Roots type, sits on the top of the intake. A couple of US companies are working on one, nothing yet.
I believe a twin turbo set up on this engine would be the best. Some internal engine mods would have to be performed to go this route. The Supercharger can be bolted on with no inner mods.