Another option for ducting is to look at what's available from the local hardware stores (Home Depot, Lowes, Ace, Sears, etc) in their shop-vacuum supply equipment parts. I've found a part at Hm Depot that can actually fit inside the Challenger T/A front spoiler sections (with very minimal massaging, and perhaps use epoxy glue to hold in place).... its only 2.5" diameter for the hose, but the unique advantage is that the duct tube is shaped at an angle (about 30~45 degrees) so that the hose can be attached and routed parallel to the ground. So, look at that option for also mounting to the cool AAR TransAm front spoilers. (You can purchase the 2.5" diameter hose from those stores, as well, in either 7' lengths or little longer. Or else, purchase racing duct in 2.5" diameter from racing outlets. I'd imagine that 2.5" diameter hose is sufficient for our maximum speed events where needed... unless you can get over 125 mph routinely.)