(03 Nav) Theres a small coolant hose that starts by the thermostat and runs up to the top pass side of the intake manifold. I'm pretty sure its there for emission reasons. I've bypassed them on other vehicles to help keep the intake air temp down. The hose is leaking and i'm thinking about connecting the hose off the lower end of the 'T' on the intake manifold straight to the start by the thermostat. I think this may help keep the manifold a few deg cooler.