Porsche Cayenne V6 2008 Service Information page 62

Fuel, Exhaust & Engine Electrics
1 - Pre-catalytic converters (ceramic substrate)
2 - Decoupling elements
3 - Main catalytic converters (metal substrate)
4 - Crossover pipe
5 - Muffler
6 - Exhaust tailpipes with trim
Page 2.32
Cayenne S Exhaust System
The new Cayenne S features an enhanced exhaust system. To keep
emissions to a minimum, it is important that the catalytic converter
reaches its optimal operating temperature quickly. To achieve this, the
exhaust manifolds in all Cayenne models are short in order to use the
high exhaust emissions temperature to heat the catalytic converters.
The modified pipe guide on the exhaust manifold has also resulted in a
significantly improved torque. The redesigned connection of the exhaust
tracts to shorter, air gap-insulated exhaust manifolds means that the
catalytic converter heats up faster due to the reduced thermal mass.
The weight of the entire system has also been reduced by other
measures, e.g. the use of new pre-catalytic converters and pipes with
thin walls.