Big Rig Power's 
dd15 Exhaust Manifold

Expansion and contraction:

Due to the intense heat generated by the combustion process, exhaust manifolds undergo frequent temperature changes. This results in the manifold expanding when hot and shrinking when cool. Over time, these cycles cause stress on the structure, leading to cracks and damaged components that negatively affect both engine power and fuel economy.

Cracked welds:

The quality of the welding used to connect various components of the OEM manifold can vary greatly. As the welds endure the high temperatures and stress, they may become brittle and begin to crack. These cracks reduce the manifold efficiency and may cause exhaust gas leaks, thus hurting overall performance.

Pipe leaks:

Aging OEM manifolds can also experience leaks in the pipes, flanges, and gaskets that seal the exhaust system. As a result, exhaust gases often escape before they've passed through necessary filtration systems. Consequently, this leads to increased emissions, the release of harmful pollutants, and lost power due to improper gas flow.

Impaired engine performance:

Aging OEM manifolds can also experience leaks in the pipes, flanges, and gaskets that seal the exhaust system. As a result, exhaust gases often escape before they've passed through necessary filtration systems. Consequently, this leads to increased emissions, the release of harmful pollutants, and lost power due to improper gas flow.