PDI C15-Acert MidMount ManifoldThe Big Boss Exhaust Manifold is designed to maximize the exhaust air flow, to reduce turbo lag time, and cool exhaust temperatures. In the design of the manifold, each port is analyzed and tested to provide a balanced flow to the turbocharger. Big Boss Exhaust Manifolds produce, on average, a 20% airflow increase over a stock manifold, cooling exhaust temperatures by 75 100 degrees. PDI manifolds are a big part in maintaining the best exhaust