Porsche introduced all 996 C2's with conventional cable throttles while all C4's were equipped with E-gas throttles. This was for the model year 98 in Europe and 99 in the US.
 
The IPD "Y" designed Cable plenum is a direct factory replacement of the OE "T" style air distributor. The IPD Plenum provides impressive max horsepower gains of 28 in the mid range and an additional 12 horsepower on top.
 
The IPD Plenum is the absolute single best modification that can be installed on these early under powered 996 Carreras and will transform your Porsche driving experience.
 
Installation is relatively easy and straight forward for mechanically inclined DIY customers although IPD strongly recommends having a qualified Porsche technician perform any IPD Plenum installation.
To confirm whether your Porsche is a Cable or E-gas throttle simply look at your throttle body for either a black electronic module (E-Gas) or a conventional spring / cable throttle control.