Aluminum Ultra XP Circle Track Carburetor 750 CFM 4150 Mechanical Secondaries Shiny Gasoline HolleyXtreme Performance Holley Ultra Xptm Circle Track Carburetors! Ultra Xp carbs are up to 38 percent lighter than our traditional race carbs, have fuel capacity that is 20 percent greater and 30 other new features! They're available in our Hard Core GrayTM hard coat anodized finish with BlackTM billet for improved corrosion protection & also available in natural tumble polished aluminum with BlackTM metering blocks and base plate. The Aluminum Ultra Xp