PDI Turbo Elbow Kit 90 Degree* Required With Turbo & Manifold Purchase on 3406E, C15 & C16 Applications Our 90 degree elbow kit is designed to have a balanced airflow and keep exhaust temperatures within the elbow the keep overall temperatures down. This part has been cast to ensure no weld breaks or issues. This part is required when purchasing a turbo and manifold on a 3406E, a C15 or a C16. Combining the PDI turbo and exhaust manifold will increase fuel efficiency, horsepower