Machined Ports: These manifolds have both the inlet and the outlet ports machined to match the factory ports. This allows for maximum flow, without compromising the integrity of gasket sealing. Auxiliary Ports: An Exhaust Gas Temperature (EGT) probe port is incorporated into each manifold for easy installation of gauges or testing equipment. There are three additional cast in bosses provided to allow for alternate testing points. Hassle-Free Installation: These manifolds are compatible with the stock up-pipes, which allows the manifolds to be installed without having to remove the turbocharger down-pipe or the up-pipes.