Ford Fiesta ST Hard Pipe Kit701550 DESCRIPTION Replacing the factory plastic tubing with 2. 5" mandrel bent piping, the COBB Fiesta ST Hard Pipe Kit removes restriction and improves airflow to the engine of your Fiesta ST. The COBB Fiesta ST Hard Pipe Kit consists of single piece pipes made from mandrel bent aluminum tubing on both the cold side and hot side of the intercooler. The results are weld free pipes from the turbo outlet to intercooler inlet and from the intercooler