With the port profile machined to suit ported heads these are a simple upgrade to maximise airflow in all conditions. Available in two lengths, 79mm and 67mm, the shorter of which is required to fit a Process West billet plenum to a GC8. The upper flange surface is O-ringed for a perfect seal to either a stock or aftermarket plenum. Fuel injector ports are machined in such a way that either 11mm or 13mm diameter injectors will seat without needing any adaptors, just use the supplied Viton O-rings as required. Fuel rail mounting points are the same as stock, so it is possible to use this with other aftermarket fuel rails.