It is funny that some car magazines know more than Porsche knows.
5.5 l? Doesn't make much sense, don't you think? The Cayenne has two watercooled turbo chargers...raising the power to 600 HP without displacement mods is no big deal.

BTW: did you hear the latest news? The Cayenne MY 2010 gets wings and flaps and can fly.

Don't take too serious what car magazines predict what happens with Porsche in two or three years. Porsche is very quiet about new projects.