Stock Versus CFM Product But with the CFM Plus 7.3L Intake Manifold System we eliminate that heat tranfer by separating the two flow path structures. Our turbo exit elbow is manufactured from cast aluminum to handle the extremely hot turbo exiting air and high turbo pressures, but the cool air retruning from your intercooler is now insulated from under the hood heat and kept from any turbo heat transfer. Diesel engines thrive on cooler air and only our intakes can deliver it! Cooler air means more dense air which results in lower EGTS more power and performance and better fuel economy. A cast aluminum intake acts as a conductor and transfers heat into the air flow at a rate of 900 times greater than our composite material.