With the manifold in place, we installed the injector rail and the TPI runners. There are dedicated left- and right-side runners, even though they are interchangeable. The runner with the EGR passage (arrow) is intended for the passenger side. It’s best to assemble both runners and the plenum with all the bolts before tightening anything. You will have to leave the valve covers off to reach the two bottom bolts for the runners. There are three different lengths of metric, Allen-head fasteners used on the TPI.