The 996 3.6L X51 package was typically found on the "40th Anniversary" limited edition cars (MY 2004) but could also be special ordered by performance minded customers. The X51 engine package increased horsepower from the standard 316 up to 345.
The X51 Carrera's came equipped with a variety performance upgrades, both internally and externally, that made the cars very desirable for Porsche drivers looking for something closer to the GT3 experience.
The X51 engine package was blessed with many wonderful internal performance upgrades but Porsche still utilized the factory air distributor opening the door for the IPD Plenum to provide even more additional power.
The 996 X51 IPD Plenum is designed to use all the pre-existing factory hardware and OE 74mm throttle body. The revolutionary design of the IPD "Y" style Intake Plenum increase horsepower by 24 and torque by 22 (at the wheels).
The X51 Plenum is a direct bolt on replacement and installation is relatively straight forward for mechanically inclined DIY customers although IPD strongly recommends all Plenum installations be performed by a trained and qualified Porsche technician.