PRE-order Factory exhaust manifold have a very small runner cross-diameter and are extremely restrictive when pushing higher boost levels on both factory style and upgraded turbos. Due to the high exhaust backpressure, the exhaust valves are forced open and combustion misfires occur. With this manifold cross section and overall design the back pressure is significantly reduced. This results in more power and lower exhaust gas temperatures. Factory exhaust manifolds completely choke out at around 900hp. These manifolds are capable of 4-digit horsepower easily.
By keeping the original flanges, the turbos fit perfectly to the manifolds without any modifications, and the cast design greatly reduces the chances of warping.
As always, correct tuning and welding is required when changing manifolds. Comes with both left and right side manifolds.