What is the purpose of the EGR pipe when fitting one of the reverse single throttle plenums?

EGR will need to be blocked off or rerouted. Some of the wiring loom will need to be extended (IAC, TPS MAF), along with modded induction etc.You can find more information here: http://forums.justcommodores.com.au/mace-engineering/200364-reverse-plenum.html