Porsche 911 GT3 R 2012 Technical Manual page 45

4.3.2. Configuration without exhaust pre-silencer
4.3.3. Catalytic converter
In addition to the above mentioned exhaust system configuration the
possibility exists to use a version without pre-silencer. With this
configuration the unit with the catalytic converter must be mounted in the
rear silencer.
Unit to mount in rear silencer 100 cells
42