I have a header on my 3. I installed a heat shield to keep the excess heat from the SU's. I also thought it would be a good idea to run a duct from the radiator shroud up to the mesh/foam air filters. I used a piece of corrugated plastic duct tubing that I thought would do the job but found out in a write up by Ken Gillanders that the turbulence caused by the "corrugated" duct reduces the air flow by half! Mine is just a street car not a racer and I don't know how much difference getting cooler air to the carbs really makes but I'd like to build something that would help keep the under hood temperature down for the carb intake. Any ideas or pics of cold air duct setup?