AC fuel rails high volume fuel rails are CNC-machined from t6061 billet aluminum. Ac fuel rails feature a 5/8" - inch fuel bore capable of flowing the most fuel to support most high-performance engines than any other. This large bore dampens the back pulse for oversized high output injectors. Easy to drill-completely compatible to stock. AC fuel rail rail comes with an additional port for nitrous set up or for external - AC fuel regulators-easy to install. AC fuel rails comes with fittings to retain stock fuel line