Jim Bell was running flow tests on various 4.6 Two-Valve modular intakes when we visited. At bottom is a stock 4.6 Mustang GT unit. As the duct taped number indicates, it flows a modest 536 cfm on KB’s flowbench. The elephant trunk at top is the KB intake ducting from their standard 2.1-liter Two-Valve kit. It flows substantially better at 782 cfm, but that’s still not enough to support major power initiatives.