Quote:
i believe to know that it has 750 hp!!!! but a more powerfull Cayenne is in progress at Gemballa
To my knowledge, the engine of the Cayenne Turbo is good for up to 600 HP without major reliability problems.
Of course only if you don't do off-roading in the desert at Death Valley temperatures or if you don't tow a trailer with a yacht on it.
I'd say that around 500 HP don't pose any problem to the Cayenne's reliability. Everything over that power figure should be taken with caution because off-roading and towing put a lot of stress on the Cayenne's drivetrain/engine/tranny.
The Porsche powerkit for the Cayenne Turbo is rumored to have something close to 500 HP but it might take another year or two until it'll be available.
If Porsche is clever, they offer a retrofit kit too.