Is it possible to use metal hose ducting instead of the plastic ducting to use for ramair setup. At work i noticed air ducting from the ovens protruding into the ceiling. I think they were about5 inches in diameter. How large a diameter should you use? The metal ducting looks more sturdy also will it hold up to the ramair effect? I heard with the plastic ducting you have to stretch it or you will lose the ram air effect.

1991 Z28 1LE 5.7 Auto.

 

I think you want something larger like the 5" you say, I don't see why you couldn't use metal tubing as long as you can route it easily and with it being that big of a diameter. Just make sure it doesn't come in contact with the battery terminals.